pumkin, if a Glock cannot handle 9MM +P+, I wonder what pistol could? I believe many, me included, would agree that the Glock is one of the most rugged, durable, heavy duty pistols produced.
While I have no horse in this race, FWIW, I'll just pass along my personal experience over a period of years with 9MM +P+ ammo. I have an old copy of information provided by Glock to Law Enforcement agencies reference the Glock's ability to safely fire +P+ and other ammo. With reference to acceptable ammo, it is not the same information as provided in the commercial owners manual. Glock indicated that the +P+ would not decrease the survice life of their pistol. Within my humble experience, LE agencies do not tend to issue ammunition that will be dangerous to officers or the public, or significantly decrease the service life of authorized or issued weapons, etc. Although a lot of 9MM +P+ finds it's way into regular commercial channels, the +P+ is sold to agencies on "hold harmless" type agreements. I suspect millions of rounds of 9MM +P+ must be produced every year by major U.S. ammunition manufacturers in order for it to be profitable for continued production.
Anyway, I have shot a significant amout of 9MM +P+ in Glock, HK, Ruger, SIG, S&W and 9MM 1911 Colt, Kimber, Dan Wesson and Springfield pistols. In the case of the S&W and Rugers, I have also used the +P+ in the S&W 547 and Ruger Sp-101 revolvers. without any detectable excessive wear, damage or other issues. In short, I would not hesitste to use 9MM +P+ ammo produced by major American manufacturers in my Glock 9MM pistols...ymmv
COTEP 640, NRA Life