I haven't fired any 9mm compacts, though (just a regular sized Glock). I definitely will not be purchasing a subcompact (unless a .38 revolver).
I think we need some definition clarifications - Glock considers (for example, in 9mm) the 17 full size, the 19 compact and the 26 subcompact (the 26 is the base size for the "Baby Glocks").
In the end, price/effectiveness will be the determiner. I want to be able to practice frequently. Is there anyone here who thinks the .38 or .380 cartridge is ineffective for self defense? Or is this really just a case of which option is the best out of several good options?
Carrying a handgun is already a compromise. Once you get into legitimate defense calibers (and I consider .32 ACP the absolute floor), there is the law of diminishing returns. If you can shoot the eyes out of a target with a Walther PPK, but cannot hit the side of a barn from inside it with a Desert Eagle .50 AE, by all means carry the Walther - a single hit with a .22LR is worth any number of misses with .357 magnum or .45 ACP. However, once you get to "carry", do you mean holster or CCW? Open carry in a holster, should be Glock 19/Sig P229 size gun an up, in my opinion, and you can pretty much pick your poison (including 4" bbl .357 magnum revolvers - still a fine choice in the 21st century).
For CCW, that same gun size, Glock 19/Sig P229 is almost the biggest you can go, and even then, you're looking at clothing/holstering options that are more restricted in a smaller gun.
In any event, there are several quality guns (of which the Kahr PM-9 is only one example) that gives you the option of carrying a wide variety of full power 9mm defense cartridges in the size of a pocket pistol.