I agree with "your first glock will not be your last"! I am already saving for my 2nd glock and I have only had my first for less than 4 weeks.
The thing is, you can shoot .40s&w out of your 31 with just a barrel swap. 9mm with a Lone wolf conversion barrel and 9mm magazines..... And .22 with an Advantage Arms kit.... So 4 calibers, one gun.