For Joe Gunowner who shoots 200 rounds a year, ammo choice probably makes no difference whatsoever. But if I, a moderately-skilled shooter who carries, can afford to change brands to gain 5% effectiveness while I continue actively training, why wouldn't I? I suspect for the more proficient shooters here, a 5% effectiveness increase may only be possible through gear/ammo choices.
I'm not dumping my HST2 supply and I agree 100% with your premise. One-Shot-Mega-Kill rounds are no replacement for skill but I see no harm in chasing a better round while continuing to train.
I understand the "training trumps all" angle. I have a few hundred hours of that myself. And yet, nobody reputable recommends carrying ball ammo when well-designed JHP is available... probably because there are good reasons for doing so (safety is the first that comes to mind for me - more likely to remain in the body due to expansion).
Since the main problem with the new 147 seems to be unreliable expansion it is easy enough to test whether yours reliably expand by shooting some old jeans laid over some gallon water jugs (water is roughly the same density as the average human tissue). The SMEs look down on me for doing so, but aside from water I'll also shoot into a mixture of 3 parts water to 2 parts 70% rubbing alcohol - a concoction with about the same density as body fat (and a more difficult medium for bullet expansion).
This won't tell you precisely what kind of penetration you'd get in ordnance gel, but it is an easy pass/fail test of expansion.
Not an ammo SME, but I've shot over 15,000 rounds through a P365 and have done a bit of backyard ballistics testing with it. I wouldn't hesitate to use 147 HST in a P365 that reliably feeds it (some examples don't - Sig has a couple different P365 feed ramp designs). 147 HST wouldn't be the defense ammo that I'd go out of my way to purchase, but I wouldn't throw away a case I already had.
Personally I went with 124 +p HSTs when my sole focus was reliable expansion, but if I had it to do again I'd get 124 +P Gold Dots for a bit more penetration (at the expense of just a tiny bit of expansion).
^This
Critical Duty doesn't always expand in 3" barrels (Hornady created the critical "defense" line to fill that niche, but I don't believe it was intended for barriers like autoglass).
Thanks for the detailed reply. I have decided to move on and go back to the Speer 124gr + P Gold Dot in my G19. Tried and true. I have several boxes on backorder and will change out my ammo when it arrives.
I use 124 gr HST standard pressure in my P365. I'll stick with that for the forseeable future.