The trouble with going by what you hear or read is that it may or may not be true.
There are pistols that can "switch uppers". My G23 and G32 can do it all day long. They are the same frame and slide just different barrels. My G20 can shoot 10mm and 40S&W and 357SIG, the latter two with aftermarket barrels. My G32 and G23 can shoot 9mm with my aftermarket barrel. Etc, etc, etc.
As far as shooting YOUR handloads in a Glock there will be no problems as long a you don't do a few things: Don't use cases that someone has managed to bulge. Don't use the original Federal 40S&W cases which are headstamped- 40S&W FC. The later good Federal cases are marked FEDERAL 40S&W. Do make sure you have enough neck tension to prevent bullet setback.
My G23 has over 15,000 rnds through it and all of them have been my handloads with over 90% of them being loaded with Lee 175 TC cast bullet. This with the factory barrel. It is my USPSA gun. Never a problem, not one.
As far as "hot" loads go my 40S&W defense loads feature a 155 JHP at 1200fps (over a chrono). No bulges there either.
And since I'm here, the Beretta locking system is a "tilting block" locking system. And it makes no difference in what you feed it