As models go, it looks like they did a good job. Perhaps better detailed than the Kato one, and more correct for the 1950s (especially with the coal tender). Paging @robert3985 for in-depth analysis on how accurate it is and comparisons with other models.
Another Big Boy eh?
First off, Kato's model isn't a "Big Boy" model, it's a "4014 Excursion Service" model that happens to be based on a Big Boy. This is because it IS a very close model of the restored 4014 as it was when it made its first excursion service appearance several years ago during UP's Sesquecentennial Celebration in May of 2018, but is is NOT an accurate model for an original Big Boy when in regular freight service. For running a modern steam excursion train with passenger cars behind it on your layout, the Kato Model is THE most accurate model to have. This means it has modernized boiler cladding (much simpler than the original), different steam piping sizes and fixtures than the original, especially evident at the rear engine's cylinder/valve assemblies and at the curve of the steam piping at the front engine...welded together and not one-piece as was the original piping. The Kato 4014 also has an entirely correct Challenger tender, since the tender that's on the present-day 4014 is the tender that belonged to the 3985 Challenger when it was running.
Good points on the Kato model are the really nice separately cast add-on plastic parts, such as the handrails alongside the boiler, which have cast-on electrical junction boxes (!) in their correct positions as well as a wealth of piping detailing cast-on to various chassis parts that you have to really squint to see, but...they're there! I also give credit to Kato for modeling just the 4014, and not modeling a "generic" Big Boy...it's pretty obvious they took great pains to take measurements and work from photos of the real deal, and it IS perfect for running their passenger cars and dynamic-brake equipped diesel behind it representing a 21st Century excursion-service 4014 to run on your modern layout. I also like what Kato is doing to eliminate the "empty air-space" between the firebox and trailing truck on their 4014 and their FEF-3's. Looks great!..and adds a lot to their N-scale models looking much more massive than any other N-scale steam locomotive (including brass).
Bad points for the Kato 4014 are the cast-on piping details on the smokebox. Obvious cost-cutting shortcuts and these details look really bad. Also, cast-on throttle linkage on the engineer's side. It's such a prominent feature...but, the bean-counters at Kato obviously said "No"...or "iie". Evidently Kato realizes this because photos of the engineer's side are hard to find. I also don't like the shallow, flat-bottomed stacks.
The second-best 4014 Excursion Service model to have is the BLI 4014...However, it has the original 1941 to 1959 boiler cladding and other details that designate the "core" of the model as being modeled from the original boiler cladding and steam piping configuration. However, like the Kato model, the BLI 4014 has no ashpans (although it retains the ashpan handwheels on the engineer's side...easily removed however) It also has the obviously original steam piping fixtures coming out of the rear engine's cylinder/valve assemblies...heading to the front engine's cylinder/valve assemblies. It doesn't have twin dynamos as the present-day 4014 has and that the Kato model has. Its tender has a toolbox on the engineer's side (an added piece) that is on Challenger tenders, but not on Big Boy tenders and has a modernized, safety-applianced oil bunker that was applied to the 3985 to comply with various safety and ecological regulations several years ago when the 3985 Challenger was running. These added pieces make it look more like the modernized 3985's tender, but the model's tender core is a Big Boy tender.
If you're wanting a model of a Big Boy to operate on your 1941 to 1959 time-period layout, forget about the Kato 4014 since it's a model of a specific, restored Big Boy that is significantly different than original Big Boys were.
Some (not all) of the BLI Big Boys are the ones to get for 1941 to 1959 Big Boys. Stay away from their two Excursion-Service 4014's (obviously), and their Kenefick Park 4023 Version...and either of their two foob Two-Tone-Grey Versions since there were never any TTG Big Boys. You have a choice between two "as-delivered in 1941" numbers, #4007 and #4012 or "Unlettered". These have different separate piping on the smoke boxes and finned aftercooler piping on the handrails of the pilot...AND two "2nd run in 1944" numbers, #4021 and #4022 or "Unlettered". These have Wilson Aftercoolers behind the front fascia of the pilots (no finned aftercooler piping on the pilot handrails) and different separate piping on respective smokeboxes.
Good points for the BLI Big Boys is the difference in detailing and paint for personal preferences, time periods, locations and "foob" schemes. They offer 5 different versions with different parts. This includes two versions for proper in-service running between 1941 and 1959...one version for early Big Boys (pre-1944) with finned aftercooler piping on the pilot handrails, and one version for 1944 and later with no finned aftercooler piping. After 1944/1945...all Big Boys were equipped with Wilson Aftercoolers, which eliminated the easy-to-damage finned aftercooler piping on the pilot handrails.
More good points for the BLI Big Boys are the separate piping details on the smokeboxes, and the separate throttle linkage on the engineer's side as well as very nicely done separate cast plastic piping and detailing. The cab interior is also very nicely done as are the opening cab windows and the lit cab. I also liked the stack details included with the model
Bad points for BLI are some of the cast-on grabs are obvious cost-cutters, such as the vertical handrails on the cab sides, and the grabs on the front lip of the cab roof...which are just elongated tabs of metal. Also some of the piping on the smokebox is also obviously cast-on and is especially plain to see when compared to the separate piping right next to it. I also don't like the excessive "air" between the bottom of the smokebox and the trailing truck which is typical for most N-scale steam engines..but I still don't like it. I hate the bright brass smoke generator parts that stick up inside the model's stacks. Since the smoke generator is easy to remove, mine get removed...and the stacks without the bright brass parts look excellent! And, the smokebox & firebox colors are completely wrong.
Mechanically, I can't compare the Kato with the BLI since I don't own a Kato 4014 and I most likely never will. All my BLI Big Boys run flawlessly, although I prefer the Soundtraxx Tsunami decoders on my Athearn Big Boys over what comes out of the Paragon 4's. Both pull 35 cars, and since that's the upper length limit of 40' reefers with a caboose and a Big Boy, that's all I care about.
Looking at the photo of the Minitrix Big Boy (from the engineer's side) shows me several things that look very good and some things that look just average.
Good points for the Minitrix Big Boy are separate piping...cast plastic attachment points with carefully bent wire pipe (not simple wire bendings like BLI's) that look very nice. Separate throttle linkage running along the engineer's side of the loco...including separate throttle attachment point on the smokebox...just like BLI's. Separate cab vertical rails at the rear of the cab and at the front cab roofline...looks like cab windows that open/close...and, the color of the smokebox & firebox look much more prototypical than on BLI's.
Hmmmm....it actually looks like BLI's model...with a few improvements. Some of the details are EXACTLY like BLI's...even how the boiler is attached to the chassis is the same, and the interior of the double-stack looks to be identical, having identical supports and a notch at the front for press-in smoke deflectors in down and raised conditions...as well as the fit and shape of other parts I can see...exactly like BLI's.
Bad points for the Minitrix Big Boy looks like the flanges are bigger than on either Kato's or BLI's, and that damned smoke-generator bright brass ring in both stacks. However, looks like the detailing is just a tad better on the boiler than BLI's...not the cast-on details, but the add-on details, but the flanges look bigger, and the tires look wider.
For a 4014, go with Kato. The Minitrix model isn't close to a present-day 4014...but, if you want a Big Boy that represents Big Boys from 1941 thru 1959 (hopefully Minitrix will offer the finned aftercoolers on the pilot handrails too with first-run engine numbers), then, from a details standpoint, both the BLI & Minitrix models look to be nearly equivalent.
The Athearn Big Boys are still not too bad, and all of mine run without any problems...Challengers too. Not sure why some buyers have problems with them...and with the BLI models, but I have never had a quality control problem with either brand.
I hate the monkey-motion articulation on all of these models. If my Key Big Boys would have pulled more than a dozen cars, I would have kept them and collected them...just because of the proper articulation...and yes, I do know why the non-brass models have it...to appeal to a larger market section...but I still hate it, not just because of the way the models look in a curve, but because of the way they look when viewed from the side...all that dead air under the boiler.
I'll do a more complete comparo when more photos are available of the Minitrix model, but...I'm pretty sure that it's identical to the BLI models in a LOT of ways...I mean "the same".
Cheerio!
Bob Gilmore