Non-violent decapping of live primers usually doesn't damage them. (The one exception is factory primed military cases that have a primer crimp.) It is actually recommended by manufacturers that primers receive a tiny amount of crush beyond seating to touch the anvil feet to the bottom of the primer pocket. This is to set the bridge (see
this article on primers). For that reason they are designed to withstand a bit of constant pressure between the cup and the center of the anvil, and that's where decapping pin pressure is applied.
Some primers seem to be sensitive to being killed by solvents and some seem to be almost completely immune to them. I've seen a report of primers killed by raindrops falling on them in loaded ammunition that was nose down in an open box. I've also seen test write-ups where they've survived a week or two of submersion in various liquids and solvents and still worked fine. Apparently the varnish coatings have variable effectiveness. I've never succeeded in killing a primer because I failed to wear gloves while handling them, but if you are a "ruster"—someone whose skin oils have a lot of salt in them that rusts all non-stainless steel you touch—then I would wear the rubber gloves anyway.
I expect a primer that has been decapped might have cracks in the sealant, so I wouldn't use such primers in ammo for an expensive hunt or for a match or any other kind of must-work application. But as others have already commented, there is no point in wasting them when a lot of non-critical shooting is there to be done.
The inertial pullers are inexpensive and work well, and for lubricated lead bullets can be the only way to go because of the grip issue. But you don't want to pull large numbers of jacketed bullet rounds that way. The Hornady Cam-lock collet puller is the one to have for large quantities. Instead of screwing the collet closer in by hand, as you do with the RCBS and Forster collet pullers, the Hornady closer has a little handle you just press down from vertical to horizontal to clamp the bullet. It works great and is way faster to use than the other style.
Any collet can mark a bullet, but, as Harry Pope said over a century ago, the base steers the bullet. As long as you don't damage the base, accuracy is not usually compromised much. A small amount of marking or deforming of the nose usually has no adverse effect until you get to very long range where the resulting irregular small reductions in ballistic coefficient can cause some vertical stringing. But I'm talking 800-1000 yards there. Even up to 600 yards, people have shot collet-pulled 173 grain Lake City match .308's in competition and not felt disadvantaged over anyone else firing new copies of that same bullet. For all but benchrest shooters, the effect of collet puller marks on jacketed bullets is going to be hard to find on paper. The Lee Factory Crimp die is a collet that intentionally indents bullets even more than the collet pullers do, and it doesn't adversely affect accuracy at more common shooting ranges. Indeed, it can actually improve common range accuracy with some loads.
