I used the Q4 this year on my 08 750. The track I go to most often is not really fast but is more of a technical track, really fun. I was getting 1-1.5 decent days out of the rear. They are very sticky though and warm up very fast without warmers. I had some oh crap moments that I just pushed the bike down and hoped for the best and they didn't let me down. I had one day in the rain and if the track has standing water they weren't great, obviously, but damp conditions they did just fine for me. Anyone else using Q4 on the track? What have been your experiences?