David reportedly stopped a giant with a rock. Anecdotal evidence that a well placed round, no matter how diminutive, can stop a bad guy.
There are also other real world reports of mouse gun ammo being deployed successfully.
So how far down the scale as far as stopping power one decides to go is really a personal decision that should be based on ability to actually carry the gun and the ability to place a shot. It is not practical for me to carry my 12 gauge 870, so I usually carry a compact 1911. When the 1911 is a bit bulky for the situation, I have my 3AT on me.
As for reliability, with the 3AT it can be a crap shoot. I say go for it. Buy the gun and shoot it like you stole it. If it is reliable after 300-400 rounds, it is good to go. If you have problems, you may have to work through them.
I think the question you need to ask is, can I find/afford 300+ rounds of 380 to determine if the gun is reliable.
And lest someone think I am off base for suggesting 300-400 round break in, that is my personal opinion for ANY carry gun, not just a 3AT.