I think you've got a good point. I tried M2TW demo, on a Autumn 2007 Direct X 10, dual core system with 4GB RAM (but with Vista). I saw choppiness and control issues, turning down graphics settings, slightly improved things but rather defeats the point of their development effort. Result, no inclination to buy M2TW, just stick to RTW which runs smoothly even at high detail settings.

There's no performance revolution going on at the moment, which could be expected to rescue a poor implementation.