You will get wear marks at the contact points. Over time, it will show on the gun.
This is my old Commander that rode in a Blade Tech IWB daily for over 10 years, and was constantly drawn and reinserted with use. The "black" streaks are actually polished chrome, and look like a mirror.
Now while that might not look all that great, if you look at the rest of the gun, the finish is still in good shape, and to put things in perspective, the gun was originally blued, and lasted less than a year in a couple of good leather holsters before it was badly rusted. I had to have it polished out and the gun hard chromed. I got the Blade Tech soon after, and between it and the hard chrome, 99.99% of the rust issue went away.
I still have both the gun and the original BT holster, and even after all this time, the BT is still in great shape and what Id use to carry the gun in if I still carried it.