FWIW:
I have the P99c/AS and the P99/AS.
I prefer to cc the compact, but under certain conditions I might cc the fullsize, so I was hoping to find a iwb holster which would do the job for both.
I wound up buying a FIST Kydex holster. Another member here posted the pictures of his FIST holsters in an earlier thread, and I checked them out. They are about the "slimmest" iwb's you find, and the price is IMO very reasonable.
When I ordered the FIST Kydex iwb I asked them if the holster would fit both the compact and the fullsize P99's. The person taking the order said "no problem, we'll cut for the compact, and mold for the full-size".. No extra charge, and I think the price was $34.95 + shipping.
When the holster came it is certainly not the prettiest holster I've ever owned, but what it lacks in appearance it more than makes up for in performance.
Both of my P99's fit perfect in the FIST, lock in with a satisfying "snick" and you can hold the holster upside down with the pistol in it and it will not fall out. Yet, the firearm withdraws very easily.. The holster retaining clip seems of excellent quality, and is designed so that the bottom lip "locks" under the bottom of your belt, so stays put when you draw the pistol.
I would recommend the FIST Kydex iwb holster without reservation. The folks I dealt with at FIST seemed professional and courteous.. In the future I hope to order another identical holster for both my J-frame Smiths and D Frame Colts..
Check 'em out.
Best Wishes,
J. Pomeroy