"It's my understanding that the Glock 20 is the only 10 mm that does well over years of shooting"
Yep, you heard wrong. In fact, that statement is very wrong in at least 3 ways:
1. It implies other 10mm won't stand up to many thousands of rounds - incorrect
2. Depending upon how you define it, the Glock cannot and does not "do well" for even 1 shot, as anything that horribly unergonomic (i.e. grip angle) is incapable of "doing well", in my view, relative to the much much higher quality competition such as Dan Wesson, Tanfoglio etc. In addition, their crappy guide rods will often crack after less than 100 rounds on a new gun - first hand experience. I would say that's not "doing well" for more than the tiniest, shortest time frame, let alone the long term.
3. If anything, of course - plastic framed guns like the Glock and Witness polymer will not hold up over the long haul like steel guns (1911s, Witness steel, 610, etc), so it's exactly backwards - that's just the fundamental nature of the primary materials used which cannot be overcome by any amount of koolaid.