The couplers look incredibly good in person. I got to inspect the SD40-2 on Friday night at an NTrak mini-event. Not MTL but the most authentic-looking clones to date. They fully look like the real thing. S-T is looking at migrating to them but unfortunately it would take time. Possibly just newly-tooled models for now, such as the SD40-2, rather than all releases. I think they want to see the consumer response on the SD40-2 before fully committing.
That sure sounds like a positive development. I'm not quite sure what you mean by "most authentic-looking". You don't mean as in "1:1 AAR coupler", but that they look just as the N scale MTL couplers? Looking at the photos I do see that they look just like MTL couplers.
The Scale Trains' own couplers were quite oversize, and they weren't easy to couple (due to them following the McHenry design with opening knuckle and stiff plastic whisker springs). If the MTL-clone coupler they decide on using will operate as smoothly as MTL couplers I don't see anything but a very positive consumer response.
I'm s till puzzled why Scale Trains stopped making their coupler boxes ready for a drop-in MTL conversions. They did that on their "Big Blow" Turbine set, but the subsequently released models did not have that nifty design.