gatorskins are OK on weight and rolling resistance but there is better. My #1 are michelin krylions - much faster, lighter and just as puncture resistant as gatorskins. unfortunately they are hard to find right now. as an alternative i am running Specialized ALL condition pros - light, fast, and puncture resistant. I found them $50 per pair shipped on ebay here:
http://cgi.ebay.com/ws/eBayISAPI.dll...MEWA:IT&ih=007
I like to run a michelin prorace2 up front for extra speed and lightness. they arent bad for puncture resistance, too.