I have a PT-22 from 1998, and a PT-25 from 1996.
Here is what I notice in the differences between them:
No variable in reliability. I'm not dumb enough to try to run cheap ammo in a heavily-sprung rimfire pocket-pistol and then complain the gun is a POS when it chokes on it. These little guns need ammo with some guts in rimfire, so MiniMags is what I stoke the PT-22 with. I've fired a few hundred through the Taurus and have had no failures. With Federal AutoMatch, during a 100-round session, I had one incident in which the returning slide missed the next round in the magazine and closed on an empty chamber.
My PT-25 has only seen (from me) about 150 rounds, about half WWB and the other half a "blue-boxed" brand I can't recall right now. No failures.
The .22 pistol seems to produce more noise and flash than the .25 does. I assume this is because the .25 ammo is loaded with a faster-burning powder intended to be mostly burned before the bullet leaves the short barrel. By contrast, the LR ammo, designed for barrels in excess of ten inches in length, uses a slower-burner to keep it "hot" while the bullet makes that longer trip. In the shorter barrel, the powder is still well-lit and burning as the bullet makes its exit.
Both shoot to where I want them to, inside of ten yards, easy to keep them within an area the size of my fist if I really try hard.
Personally, I didn't notice a difference in trigger feel, though I suspect the rimfire gun might have a heavier trigger for the hammer to smash that thick rim.
The PT-25 holds nine rounds in its magazine, one more than its rimfire counterpart.
So, choosing one as a defensive piece gives you the following to ponder:
Ammo design to gun edge: PT-25.
Ammo performance edge: PT-25, but barely.
Ammo capacity edge: PT-25.
Cost of practice (a necessity!) edge: PT-22.
In my opinion, there is not enough of an edge to the PT-25 for you to add one to the .22 unless you are trading the .22 out for it. Even then, I'd feel just as well served with the .22 in my hands as the .25. If your .22 runs well with the ammo you use in it, buying one in .25 is pretty much gonna be redundant. If your .22 chokes just enough to give you pause, then that one would make a good trainer and the .25 your "actual gun."
I got my .22 in 2012, and my .25 in 2015. The latter was simply on a whim (actually, both were.) Each cost me around $160, if I remember correctly.
I enjoy them both.
EDIT: Gun Master, I see in another thread you say that, when you do carry the PT22 (which isn't often), it's usually backed by a Bauer .25 (incidentally, another little gun I enjoy owning.) If that's the case, I certainly see no reason to go get a PT-25, unless you just want one.
To me, there are only two possible reasons for buying a specific gun:
1) I don't have one; one would be cool.
2) I already have one; another one would be cool.
