I have seen the sites where they sell concealment t shirts. The Sportsman Guide has them pretty reasonable but the choices are only small or large holsters. I have a Glock 30 does this mean this is a small or large gun? I know it is a subcompact. What do you think and do you think this is a good deal?
I dunno. I would say that a Glock 30 falls into a large category, so to speak, because of the slide thickness. But, you would have excess room at the end because it is short. (Just my thought/experiance with "generic" sizes for holsters.)
A friend in LE tried one and liked it to carry his Glock 26. Other than that, I hope there are others who have had personal experiance.
As to which size, I'd contact the company selling them and let them advise you.
I've read of others trying the concept and liking it. Being one who believes in as many options open as possible, I'll probably try one out at some point. Why not?