I've wondered the same thing, as a keltec 32 is what I CC, and after chronographing various rounds, I've come to the realization that none of them offer enough of an advantage over others, so I just use winchester fmj because they're cheap and reliable.
At the velocities you listed, FMJ bullets should give you something like 13-14" of penetration, which should be enough for the vast majority of cases.
The fiochi HPs have higher velocity and knockdown, but I've read online before (so it may be untrue) that .32acp doesn't penetrate far enough with HPs to be effective, and that rimlock is also something to worry about with this round, so I don't bother carrying them.
Well, anything you read
anywhere could be untrue, and at least some of what you can find online is based on real data. Everything I've ever heard or read about .32 ACP has suggested that penetration will be limited with HP bullets that expand, and that's not hard to believe if FMJ really only gets you just enough penetration to start with (by the way, I favor achieving adequate penetration first with some margin if possible, although others may disagree with this philosophy). If you could find a HP that will fairly reliably open up to only the starting diameter of the bullet (0.309"), making the bullet cylindrical like a wadcutter instead of round-nosed, then that would probably be the ideal load for this caliber, all points considered. Otherwise, I'd personally stick with FMJ.
I've heard a lot of people talk up the buffalo bore ammo, but for the price ($1+ each), I don't think they offer enough increase in performance to bother with, and they're too expensive for me to practice with, not to mention being high pressure, which (supposedly) will wear out the gun faster.
For .32 ACP, that is no doubt a wicked-looking load, and I do think that it would cause more damage with its wide meplat (flat nose) than a FMJ-RN (round nose) bullet. While the probability of hitting something at all would not be appreciably greater, despite better edge-wounding, it would crush more tissue that it comes into contact with (which is especially effective on the lungs, for example), as opposed to a FMJ-RN which acts more like an ice pick. Then again, I'm not familiar enough with .32 ACP pistols to know how well they tolerate +P loads, it would be expensive to train as you'd fight without an abundance of cheaper +P ammo, and I'm uncertain as to how reliably such a round would feed. Once again, FMJ is probably the best way to go in this caliber.
I'm also not sure what guns these ammo manufacturers are using to test their ammo with, but none of the velocities I got were close to what they advertise. I was actually pretty shocked with how dismal the performance of this round is after chronographing it,
They almost certainly use guns that have barrels longer than that of the Kel-Tec P-32. Winchester, for example, tests with a 4" barrel, compared to the Walther PPK's 3.35" barrel, and the Kel-Tec P-32's 2.7" barrel. But even so, FMJ bullets will have enough velocity out of your gun to get the job done. Stick with the heavy-for-caliber bullets (generally advisable for relatively short barrels although I always do this anyway), and you should be fine.
and might possibly move up to a keltec .380 in the future because the increase in the weight and size of the gun isn't that much.
Although .380 ACP undoubtedly has more potential, I think it may be even harder to decide on an ideal load for it in some ways, as FMJ bullets will overpenetrate and probably not wound substantially more than .32 ACP, while HP bullets tend to be unreliable and may still not penetrate enough when they do expand. For perspective, it's a lot easier with revolvers and .38 Special because one could use all kinds of nasty bullets (e.g. the classic FBI load) that probably wouldn't feed and/or aren't available in .380 ACP. In this caliber, I'd probably go with JHP and hope that it penetrates enough, but I'd also be sorely tempted to make the jump to 9mm. Maybe others will have rather different opinions on this.
I haven't done any penetration or expansion tests with my .32 yet, but I plan to in the future. Sad as it may be though, it's still beats a sharp stick.
It's a small round to use on largish creatures like humans, to be sure, but make no mistake, it penetrates enough with FMJ bullets to kill pretty well if you hit something vital (and shot placement is still of the utmost importance even for a .44 Magnum).