I've had GP4000s's on my summer bike for a few years and never had a problem (the only p'ture they've had was on the day of the 1000+ carpet tack on the Etape Caledonia). My brother a wee bit heavier than me has had lots of p'tures with his. I got good p'ture free life out of my 4season tyres too. Different beasts but my conti contacts (37mm town tyres) also performed admirably, 8500 miles one front and one rear p'ture (the front is now the back and is still going). At the other end of the road tyre scale, My Bianchi came with a wired GP's great tyres and the front ended up on my Kinesis front then rear and iirc got circa 7900 miles before a p'ture and got retired at 9600 (without any further events). I went for the newer version of the tyres and suffered from quite a few p'tures, although most were pinch and I put that down to 22mm front, the rear were 24mm. All four tyres failed early in the same way (well before the wear indicator disappeared, the longest lasting got just 1200 miles), ripped sidewall. IMO conti have concentrated too much with the tread p'ture protection with the new GPs and forgot about the sidewalls.
Hearsay, but I was talking to a mate in the club last night about the Pro 3, I was thinking about getting them as a replacement. His review was they are great grippy tyres (do everything they say on the tin there) but they cut up a bit.
To sum my ramblings up

I used to be a conti fan had great p'ture free wearout of them until the last 4 base GP's and I'm looking around for something new; I looked at Pro Grip 3's but am worried they'll cut up a bit (especially before we get to summer); I think I'm going to order Krylion's.