Jeff:
I often change out the grips on my R9. I have on hand Blue CFs, Black CFs, Silver Aluminums, OD Green Aluminums, "Hyena" Brown VZs, Hogue Extreme Series, and Ivories (pre-ban). My R9 has been totally reliable with all of them.
As for the grip screws, I use rubber mini O-rings under the screw heads to keep the screws from backing out of the frame during firing.
And as for that silly 150-round "urban legend," it is totally absurd. Rarely has a comment been so distorted and repeated out of context as has Karl Rohrbaugh's "carried a lot, shot a little" comment. All he meant is that the R9 was designed to be a self-defense weapon, not a recreational target pistol. There are members of this Forum who have run more than 5,000 rounds through their R9s. The only requirement is to keep the R9 clean, let it cool down a bit after extended strings of fire, and change out the recoil springs after 200-300 rounds or so. (The recoil springs cost only $4.99 each through the company's web page.) Order a dozen at a time. In a 13-ounce pistol chambered for a full-house 9mm Parabellum cartridge, the recoil spring has a lot of work to do.
Good shooting!