Just purchased these in April - 2nd set on my Trek Emonda SL6 w Aeolus 5s - I purchased the reflective tires this round - they are awesome at making you even more visible & my first ride out, I picked up a carpenter's finishing staple. No tube puncture or anything! I highly recommend these. I'll probably upgrade to the 5000s on the next round.
I have been using GP4000 tires since their introduction, for a total of somewhere in excess of 25000 miles. They are tough, light, and terrific at cornering in all road conditions. I generally get about 3000 miles out of a set of these tires before the wear dimples disappear. This riding over largely chipseal roads. The only problem with these tires has been pointed out by a few reviewers, has to do with the sidewalls being somewhat fragile. I have only had to throw away one tire due to a sidewall puncture. It was upsetting due to it being a brand new tire, but I doubt that any tire would have survived that particular road hazard. I consider these to be about the toughest tire out there. I will continue to use them as long as they are available.
First time trying these on a road bike, in 28c. So far after around 500 miles of riding, I'm happy with the performance and durability. It works well on paved roads, rolls well, and are quite OK on some rougher surfaces as well. They look pretty good too!