I'm doing some more research on it, but it appears roller bearings on cranks are not all that unfamiliar. Supposedly race car engines use them:
http://www.finishing.com/301/90.shtml
http://forums.autosport.com/showthre...threadid=93001
However my research shows that F1 teams use high tech journal bearings.
http://www.powerenterpriseusa.net/pr...l/f1_metal.htm
As far as I can figure, piston engines cannot use roller bearings that well because they have too much orthogonal loading (Forces directly perpendicular to the axis of rotation). I don't think rotaries would suffer from this as the power stroke causes only a rotation of the parts and not a direct perpendicular movement of rotor against the eccentric shaft.
If the bearings is low profile enough, I think it may prove quite applicable to our engines.