It's never good to have your tires pumped up to max. The bad is you reduce traction, increase drag and increase a chance of flatting. The good is you virtually guarantee you won't get a pinch flat.
A simple test can convince you that a lower pressure is best for puncture resistance. Blow up a balloon hard. Drop it on the sharp point of a pair of scissors. It will pop. Take another balloon and just blow it into a round, soft shape. Drop that ballon on the sharp point of a pair of scissors and it will just bounce off.
On a rough surface, such as blacktop a softer tire will roll over the bumps; a harder tired will bounce up off the bumps. The rolling resistance, albeit only a small change, will be higher on the stiff tire. For the same reason, cornering traction is compromised on a tire pumped up to high pressure; every little bump will cause the tire to bounce and the outward force will cause the tire to slip out. A softer tire (lower pressure) will grip the bumps as the tire deforms over them, increasing cornering traction.
There have been no definitive rolling tests that prove the rolling resistance change relative to tire pressure becuase there are studies with conflicting results. There is plenty of anecdotal evidence, though, that lowering the pressure of your tires, relative to the weight distribution of your bike will give you best, most comfortable handling and traction.
