Scott,
What would be truly great is if you could offer these in a similar fashion that MTH does with much of their current Premier diesel offerings, specifically easily changeable wheels/axles so you can swap to either 2- or 3-rail wheels, interchange 3-rail couplers with 2-rail and vice-versa, and design them so that the engine itself can operate on either 2-rail or 3-rail track via a switch mounted on the underside or in a hidden compartment on the body.
Noooooo!!!!!! Don't do it!!! Building to the lowest common denominator just creates a poor, compromised model. The way Scott does it now is just fine. Design it as a two rail model and adapt it for the three rail market.
Opinion.
Works for me.