Okay, so the parabolic idea is probably gimmicky. I know I have run across them somewhere, but I just need to learn rollers again. Points well taken.

As far as the smoothness. I am thinking the larger the diameter of the rollers will definitely impact smoothness, and since I am going to build them, why not go really large (Kreitler boasts their 4.5" are very smooth, so why not. Also the way I will construct, with kiln dried quarter sawn maple, they will be VERY stable. And heavier than any machined aluminum. All good things, I think, but could be convinced otherwise.

I really like the idea of building in free motion. Consider it done. Winters here in Maine are long, and building furniture all the time gets boring... I need a hobby.