John:
For now, I'm living in both worlds. I buy MTH locomotives with scale wheels and all new rolling stock is equipped with scale wheels (I'm converting some 3-rail equipment to 2-rail). However, I've been a member of a 3-rail club for more than 20 years and currently run the scale-wheeled equipment on 3-rail track (a lot of YouTube videos on this). I also ran on a 2-rail modular layout at a show to demonstrate MTH's GE Hybrid running under DCC. I've run DCS on 3-rail, 2-rail, AC power and DC power (for testing purposes).
What I'd recommend is to choose one or the other and stick with it. The only advantage 3-rail has at this juncture is you can get away with running sharper curves (as small as 18" radius/O-36) but that comes at the cost of appearances and the loss of the ability to run longer trains. There is plenty of 2-rail equipment that can run on 36" radius/O-72 but in some cases it compromises appearance (think Big Boy or long rolling stock).
