I've raced and trained with both. Gatorskins make sense for the average rider who would rather finish without puncture. GP4000S with Black chilly is lighter, rolls and handles better, but has shorter life. I enjoy being able to change tubes on GP4000S without the use of tyre levers. Good option in the middle is "normal" Grand Prix with polybreak, from Conti. Try 24mm if you can find. Can't find article now, but tests have proven, slightly wider (24mm or even 25mm pumped at recommended pressure gives rolling resistance same or better than force and attack sets at 22mm and 23mm. I have incidentally also used these, but that little rubber scares you when sprinting and it shifts from side to side.
