I began installing the wheels on my coalveyors last night. They look and run GREAT. I know some don't care for it, but I dig the sound of the metal wheels running down the track. I had one of the seasoned modelers in the club I used to belong to tell me the single best thing I could do to improve my enjoyment of the hobby was metal wheelsets, and I am now going down that path.
I need to dig out my wheel guage and the jury is still out on overall performance (i.e. staying on the track, staying in guage, staying clean, etc.) but my initial thoughts are two thumbs up! I'm not crazy about the brass tread either, but for now it is an acceptable trade-off for overall wheel appearance vs. cost. Like Tom (I think) said, only contest models really need the "treatment" anyway, and I don't have any at this time. I'm sold at $2.22/car--40% the cost (worst case) of NWSL--especially for unit trains like I'm doing.
Question though...is there benefit/requirement to having the insulated wheel on the same side throughout? I know you would reverse them for a situation using wipers to power an EOT for example. I'm guessing it really doesn't matter but I just happened to think about it last night.