Try it out for yourself.

As I said before, I'm right around 120#, and if I put less than 110# in my tires, I may as well be riding my 35# commuter with 1-1/2" knobbies. It's like pushing a tank.

Once in a while I do get on roads that are so rough that it really will bounce and beat me up, and I know lower pressure would help me there, but I'm never on those kinds of roads long enough to make it worth changing the pressure.