I've ridden several groups - nothing current though - 2300, Sora, 105 (5600), Ultegra (6600) , Dura Ace (7800), and the new Campy Centaur 10sp. I have to say, it all works really well. Yes, there are differences in feel and weight, but its all going to shift when you hit the button. None of them have been bad in my experience - not even the 2300. So far, I prefer the Centaur that's on my bike now, but the differences are pretty minor across all the different groups I've tried. I fully expect all of them to last a really long time. I've had to replace two RDs (105 and DA), but that was the result of other problems causing the failure.