With Speer Gold Dot making a self defense load, that might make it a better carry/home defense pistol. I haven't seen testing of that round yet.
https://www.thefirearmblog.com/blog/2020/01/01/speer-gold-dot-5-7x28mm-ammunition/
I can't imagine that this is a good SD round*. Either it's fast enough to make a 40gr round effective, in which case overpenetration is a real issue, or it's slow enough to limit over-penetration, in which case it's a 40gr hollow point. No one raves about the ballistics of a .25ACP JHP (I know, an exaggeration, but still). This is a situation in which they have a caliber, designed to do "X" pretty well, and since no one actually does "X" they are forcing the caliber into the "Y" role because, it's good enough to sell some. If HK cared even a little about civilian sales, we could have epic internet wars over which is better at something they weren't designed to do: 5.7x28 or 4.6x30.
I suspect Speer will sell a enough because marketing, but this is not a use case that this caliber is good for.
I would point out here that 5.56 is considered to have real over-penetration issues for SD until it get's fast enough to fragment, something 5.7 out of a pistol isn't going to do.
*Which is not to say it won't kill someone. Rather it's a step down in just about any performance category to any of the "normal" self defense calibers. The platforms do have good magazine capacity, but they tend to be in full size guns, and full size 9mm's are creeping up on 20 rds in the mag these days (CZ P-09 has 19, pretty much everyone else get's 17 in the grip).
