Sure if you can afford it go for one of the expensive sims. The flight model in FMS is currently being updated but it's likely to take a while and there's no knowing how good it will end up.

For serious training I still use CSM V10. The sound and graphics are horrible but the flight model is excellent, both for fixed wing and helis. And it's a lot less expensive than the newer sims. I also find it easier to set up my own models in it (though that may be because I know it).

Steve