I am a 190-ish hour pilot, who has been involved with PC-based flight sims for about twice as long as I've been flying the real thing.
I own both Microsoft FS (9, X, etc.) and X-Plane 8. I have spent many hours in the former (since version 3 I think) and a few hours in the latter (mostly due to frustration in the case of X-Plane), and I find the X-Plane flight model to (a) not be realistic and (b) to be a lot harder to fly than the real thing. I admire the approach that X-Plane takes to simulating a flying "body" but I think it completely misses the mark for helicopters.
MS FS certainly has its limitations and foibles, but I believe that it would result in less "negative transference" of basic skills than X-Plane.
Dave Blevins
USA