I've pinched quite a few motors, I will say stay away from any Ebay pincher for $10. or hose clamp. I am a machinist and a couple years ago I built a similar pincher to the cheap ones on Ebay, hard to keep the sleeve round.
I have since came up with a new way and it works awesome. I would say you would probably get almost as much life out of a pinched motor as you did before you pinched it. That is if the crank and rod is not worn badly. I even pinched a motor that had sucked dirt and it ran like new. I've heard some pinchers ask you how much pinch you want. I usually just tighten mine up but not to the point it needs to be broken in. I have heard Ceo mods pinches motors but I don't know if he just does it on his own motors or not.
Rex