Do the bouncy bits at the rear make a difference? It depends on your bike. If you ride a hardtail or rigid bike, then yes. If you ride a dually, the difference isn't noticeable. Initially, you spend a lot of time looking at the rear end of your bike trying to work out what's feeling so weird, then you get used to it and enjoy the fact that most of the little bumps disappear and the bigger ones have the edge taken off them. 10mm of travel can't do a whole lot to smooth out the trail, but it can do enough in combination with a very well shaped saddle to make a hardtail much more comfortable on those longer rides.