^^ Same experience as Robert, no issues. I think the sidewall failures/rips are due to under inflated tires rolling in turns (like severely under inflated, 30-40 psi on a 23mm tire or whatever) or catching sharp objects and then later blowing out when the tubes are pumped up to a proper pressure. I'd imagine these things happen with every type of tire, the sidewalls on GP4000s aren't as durable as Gatorskins but they're much more durable than a $20 generic road tire.

I've used them for 3 years, 15,000+ miles (so probably 4 sets of rear tires and 2 fronts) and I've only flatted twice from road debris and had 0 sidewall issues. That includes a lot of races and rides in the mountains with 40-50 mph descents. I wouldn't worry.

Edit: I'm 180 lbs, I run mine 85 front/95 rear but I've run them as low as 65-70 if I forget to pump before a ride and haven't had any pinch flats.

Also, the picture in that Amazon review looks like he hit a very sharp metal object and it slashed the sidewall, which allowed the tube to eventually work its way out and pop. There aren't many tires that can really prevent that, you just have to try to avoid rolling over sharp metal or glass things on the road.