I always put LFS' ffb down to the tracks, they're way too smooth. The only reason iRacing's ffb feels better is because the tracks are all laser scanned and the bumps and dips are much more noticeable. This isn't to say LFS' force feedback is bad, take the updated Blackwood for instance, at the end of the straights where it's bumpy, the ffb is actually working quite well.
Just me?