If the reamer is correctly designed, it should be flat and non-cutting at the tip and the cutting blades should be profiled to match a proper primer pocket's profile. Conceivably, that could shorten the life of your brass if you are shooting at high enough pressures to expand your primer pockets significantly. But if you are loading at pressures that allow your brass to age until it either starts to split at the necks or suffers incipient head separation without the primer pockets getting loose, this won't be a problem.
That said, for 2000 I'd spend the extra nickel or so a case for a bench-mounted swaging tool and then have it for the rest of my life or resell it on eBay. The
RCBS is on sale at Midway right now for $85. The Dillon costs $115, but has the advantage of having been around longer. I've never used the RCBS, so I don't know how they compare in effort or setup complexity, but the Midway reviews make the latter sound similar. But the Dillon, being older, has lots of YouTube videos,
one showing how to make it auto-eject, which gets the throughput up to about one every two or three seconds. It also has plastic
inserts available at Inline Fabrication to improve case alignment so you don't get the occasional slight miss that ruins the edge of a pocket as otherwise can happen (though you will kick yourself for paying $24 for two pieces of plastic that have to be hand-fitted to your swager, in saved cases, they ultimately pay for themselves).
The RCBS unit looks like it is meant to be mounted left to right, while the Dillon is worked from one end. Both need some setup practice. The reviews suggest the RCBS can wear its aluminum casting over tens of thousands of round, which RCBS replaces cheerfully. I cracked my Dillon's casting once, and Dillon replaced it just as cheerfully, so this may be par for the course between aluminum and the high force involved. That tells me you want one of these brands that stands behind their gear if you get one.
Occasionally, I have had to swage a case a second time. It just depends how much metal was moved in the original crimp. Swaging doesn't remove brass. Rather, it just pushes it out to the perimeter of the primer pocket and a bit beyond, which raises the surface around where its ram went slightly, like a super shallow crater wall. When the case is fired, pressure against the breech face of the bolt squashes that flat again which causes some of it move back toward the pocket, tightening it a little bit. But the number that need this redo are few and far between.
All that said, it's really the immense time savings that makes these devices attractive.
