The amount of finish wear you'll experience will vary with your usage. The more you draw and holster the pistol the more wear you'll have. Also with Kydex, you have to be careful to keep the holster's interior clean. If you let dirt build up inside, it can work its way into the Kydex to form a light grit sandpaper. Fortunately, you can hose out or wash a Kydex holster. -You can't do that with leather.
Leather has its own perils because of the tanning acids used. The acids can interact with the gun's finish, especially when you add body heat and or moisture (whether humidity or actual sweat). Then again, I find leather more comfortable to wear against the body than Kydex which seems to trap heat better.
Basically holster use means wear. There's no way around it if you are going to carry daily or practice regularly. There's no such thing as the perfect rig which doesn't produce wear.
One of the things that seems to lessen wear with Kydex holsters is to spray a light coat of gun oil into the interior. Wipe away the excess and just leave a light film. I use Remsoil for that. The interior is slightly slicker than when it is dry. I feel it has minimized the wear. However, you still have to clean out the holster every so often because you don't want to the dirt to settle into the oil. Dirt in oil works as a lapping paste and that can produce wear as well. Like I said there's no perfect solution, but the light coat of Remsoil in a Kydex holster has worked for me.
