Resurrected thread, I see. And, sadly, I guess that I see why MTH and its Maryland-born founder never offered the big WM 2-10-0. The posts in this discussion have very much been centered on the Potomac 4-8-4; I may be the only one whose checkbook was open for the 2-10-0 and not the 4-8-4. I'm still surprised, Mike.
Lots of 4-8-4's around; fewer Decapods, even in real life. That WM 2-10-0 had more juice than many (most?) articulateds - like a few D&H 2-8-0's - another niche loco that would have sold anyway, I do believe - if for no other reason than its funk-factor. But, that's another thread.
All of which really begs the question as to why MTH did indeed offer the big WM 2-8-0. I have one (in NYC, granted). They were popular.