I've ridden the GP4000s for most of my 12 years of riding, with close to 70,000 miles covered on various sets of these tires. I have only had a half dozen or so cuts or punctures with these. I run a fairly typical wheel, and my tire pressure between 95 and 110 depending on what I'm doing that day. Obviously the lower pressures would be for more curvy rides, and the higher pressures for more flat rides. I must say, though, that these tires did teach me the value of carrying cash on long rides. I had to fold a $20 bill up to act as a tire boot once when I got a 1" long cut in my sidewall from a piece of sheet metal.
All that being said, I'm currently riding Specialized Espoir Elite 700x25 tires for logging training miles- I've been off the bike for a long time.