I was thinking...
What if, instead of the traditional teflon/nylon pads that are on the base of a dobsonian mount, you used rollers instead? If they were short the differential rotation wouldn't be a problem (and if it was, you could use ball bearings instead)
This would make it easier to move - also, if you used rollers, it wouldn't be too hard to put a handle on one of them and use it for a slow-motion knob - perhaps with an extension so it would be more accessible from the eyepiece. Perhaps the roller with the handle is covered with rubber, wheras the others are metal or plastic, so that the rubber roller is better able to drive the scope.
Has anyone tried this, or heard about it?
-Dave Boll