Somewhere around 45,000 through my M&P9, no issues not attributable to ammo. Still shoots well, accurate enough for what I do. Gone through a couple or so recoil spring assemblies, rebuilt the magazines, changed out a few bits, but nothing was broken. Stopped changing parts about 20,000 rounds ago - just going to let it ride now. If I get motivated, I'll have the slide die penned at 50K and do a rebuild. I guess it's in the same boat as Tactical 111's Glock - mine for life, because no one else would buy it - although it isn't for sale, and it won't die.
PS when Slavex gets here, we'll find out what high round counts are all about.