I started use rfactor since about 1 years ago, after 3 yers and 250.000 km with LFS.
At the start was a tragedy for the force feed back really different from LFS.
After some months and a lot of esperiment with controller.ini (in rfactor u can build your personal controller.ini working in oversteering or understeering and other) finally i was happy with the FFB of rfactor.
The problem of rfactor is that there are a lot of MOD and a lot of these are very very bad.
But there is some beatyfull mod that i love, for example the historical or the enduracers.
Here the Porsche 2.4L in action with mine:
http://www.youtube.com/watch?v=bwA-c4CbirE
But LFS is LFS, it's best respect rfactor of course but after a lot of KM i cannot race every time with the same cars in the same tracks, is started to be annoyed about that. I'm since waiting for some good news (open source for track, FOR example ...).