Have been using A-Zoom in the classroom for several years now when training people on the proper procedures to make a firearm safe. A conservative estimate is that I've had 3000 people cycle rounds in various pistols, revolvers, rifles, and shotguns. Many times they would do the drill more than once. I few of the .40 dummies have some noticeable wear on the rim from the extractor and ejector, but for the most part they all have held up remarkably well.
Now if I could just find a .22 dummy that will last. I go through those little orange plastic ones like crazy. (I store the training 22A pistols with a plastic round in the chamber on which we drop the hammer as a final verification that the gun is unloaded before putting them away)
For dryfire in the M&P, I took one of the plastic dummies and cut the rim off so that it won't extract as I cycle the slide. It's basically a chamber plug to make sure that if the firing pin were to break, it would not exit the muzzle. In true double or singe action pistols, I use the A-Zoom dummies.