I'm now running Pasela Panaracer 28's with Tour Guard on my commuter and Conti Gatorskin 23's on my recreational bike. I'd say I have about 300 miles on each since I switched them.
I'm very happy with both tires so far. I think the difference in speed between the two sizes is pretty negligible. I can barely tell the difference. Then again, I'm not very fast to begin with. Maybe it makes more of a difference to a stronger rider.