The whole issue of toe overlap is a tricky one. I remember buying a bike once many years ago, the store installed fenders on it, I rode away and in two minutes caught my toe in the front fender, pushing it into the wheel and bending the fender, folding it into itself. The bike I've owned since didn't have the issue and/or front fenders so I can appreciate not having overlap to deal with. I guess with discs this would allow 26 inchers more easily. I personally wouldn't go the 650 route, just from tire availability and all that.