From what I've read and talked with fat bike owners, tire pressure can totally change a bike's handling and ride quality. Most people set the tires between 6-9 PSI, some as low as 4 PSI, but no one ever mentioned that they go over 10.
It would seem logical to me that more PSI in the tires would induce the rebound effect osco53 was talking about. make no mistake, fat tire bikes can go fast, but as with anything, proper set up will deliver a more confident inspiring ride.
Part of the reason I want front forks is to make sure the front tire maintains contact with the ground.