It's difficult from a forum point of view.
The IMS is a distinct sound kind of gurgling groaning sound.
I would be skeptical, and sometimes IMS's can be replaced and go bad again.
Basicly there is a rubber seal and inside these little ball bearings and when the seal and so on goes to hell and a hand-basket. Lot of metalic shards, chunks and so on. It's one of those
things you just really pay attention to on a 996 or even 997. Better yet folks here is a video!
YouTube - Porsche IMS Bearing Failure Explained
If you go with a factory part, I would inspect it after each track day or 8-10,000 mile services.
Remember, it depends on if you are modifed what kind of enviorments you are driving in. Oil tepm and coolent temp are different.
If you go with an up grade, the failiure or service life is a hell of a lot longer. But still you inspect things. Good luck -