Try it, you'll like it.
I use Babolat leather grips with Babolat Pro Team overgrips; an unexpected benefit I noticed is that leather grips added power to every shot. I can't explain why but it's there. There is also the firm or tight feel leather provides that is better than what other grips offer.
However leather w/out the use of an overgrip will become very slippery and frankly not very comfortable, in my opinion. So the prime combination is leather w/your overgrip of choice.