Depends what you mean by 'plenty of tread'
Agree with Yellow_Mini_Scott that having more grip at the front than the rear can lead to oversteer (not good) but if the fronts are only slightly worn I think you should be OK. I rotated my tyres front-to-back at about 6000 miles without any problems (fronts still had a good 4-5mm tread).
Anything less than 3mm on a tyre and grip in the wet will seriously suffer so wouldn't recommend it.
Rebalancing shouldn't be needed (unless wear is uneven) - balancing is done with the wheel off the car anyway
