I have a Phil Wilson Filet and Bird & Trout knife in S30v with Micarta handles. I used both extensively on a 10-day Alaskan fishing trip last summer.
The B&T was on my belt every day and used for everything from cutting fishing line to kitchen chores. The filet knife was used to clean no small number of salmon during the trip.
Both knives performed superbly! I have yet to sharpen either blade...they simply don't seem to get dull.
If you are looking for a high performance blade made with CPM, Phil Wilson is THE maker to work with.
Re the difference between S30v andS90v. S30v is more rust resistant than S90v. S90v may be a tad harder but since Phil wrings maximum performance from both CPM's, the average individual cannot distinguish between S90v and S30v cutting ability.
Phil recommends S30v over S90v for filet knives simply because filet knives are presumed to be used in wet environments and if the "wet environment" is salt water you need all the corrosion resistence you can get. Trust him. Besides being an outstanding knife maker, Phil is an avid salt water fisherman. He field tests (i.e. punishes) his knives far more than you or I would.