I don't buy the premise that you need to regularly shoot a variety of guns to be able to use something new.
I've pretty much only ever shot 1911's until I started to CC, an Xd for a few months after that, and now a PPQ. I do have a .380 and a SP101 for the woods, but neither get shot much.
Despite that, I've never had any problem figuring out friends guns. Figuring out how to eject brass from a SAA did take several seconds the first time, and I imagine I'd have a hard time breaking any of them down, but as far as shooting goes most handguns have a lot more similarities than differences.
Also - on a more pragmatic note - how likely is it that you'll ever have to defend yourself with someone else's gun? Or if you did, what are the odds you wouldn't have the few seconds it would likely take to identify the safety and type of action?
In the end they're your guns, so if you like glocks the best, I really don't think there's any good reason not to go for it. The great thing about guns is that if you ever change your mind you can sell them and get something else.
si vis pacem para bellum