If you notice a difference it would be purely psycholgical in origin. there is bugger all difference in the 'speed' of wheels. Stick with R500s, run em until your hubs are shot. Mine have a hare over 13,000km on them, with one hub complete pull-down. I'm hoping to go to 20,000km, which is about August/July. If they wear out before the GP 4 seasons I put on them when I got them, I'll (try) and eat the GP 4.