I ride with a 60mm stem at the moment and I've used a 50mm stem in the past. The bike handles just fine. It is however just a little more sensitive to steering inputs, its a little harder to maintain a straight line when looking over your shoulder although this can be a problem for anyone and when your in a full bore out of the saddle sprint its not as stable as with a longer stem but its nothing you don't learn to deal with.

Fitting a 60mm stem isn't going to make the handling impossible to deal with.

Regards, Anthony