Oh I agree you have to be accurate with anything, a hit anywhere with a 22 is far better than a miss with a 44. There is no question that I am far more accurate with the fiveseven than any of my other handguns. I've experimented with rapid followup shots with 45, 380, 9, 25, 357 and the fiveseven at 7 yards. The worst was the 25 noisy cricket, (they were all over the place) and the others were roughly the same with 80% (4 out of 5) on the on the paper and roughly half of those in the kill zone. The fiveseven was by far the best, 100% on the paper and 80% in the kill zone. The fiveseven is an absolute tack driver. Maybe more akin to a sewing machine
However...
Somewhere on this forum I read an excellent thread on shot placement and it makes a lot of sense. Shot placement is going to make the fiveseven deadly. There is another thread I read recently that was interesting as well. THis was by a cop who turned into a mortician. From observation, his opinion was that 9mm/380 took multiple hits to incompacitate someone. That critical hits were of course fatal, but smaller calibers than 40 or 45 just didn't do enough damage. Chest shots with these calibers deflected off of bone or clothing and had a harder time penetrating to the vital organs, where a 40 or 45 hit broke through. He made another interesting point, the purpose of bone is to support structure; break the bone and the structure collapses. The obvious implication is shattered limb is going to incompasitate someone faster than shreading flesh.
This is also born out by a friend of mine that was a nurse and combat medic in 'Nam, three tours. He had a lot of experience treating wounds. His opinion was that the 5.56 made far more horrific wounds than the 7.62, but... he was looking at it from a treatment standpoint. He said the 5.56, with the fragmentation made much worse flesh wounds where an AK round would just plow though. That's not to say that a 5.56 couldn't shatter bone, where the AK round would "crack" bone, a solid hit with a 5.56 would "shatter" bone in that area. The conclusion is that the 5.56 makes a makes a much worse wound to treat, but which round incapacitates faster? There are so many variables, and I certainly wouldn't want to be on the receiving end of either but I think an argumnent could be made for the larger caliber ruining somone's day quicker.
The morgue worker also was of the opinion that ballistic gel is a terrible indicator of wound capability. His opinion was that a projectile needed to be traveling at least 2500+ fps to have a temporary wound cavity do enough artery damage to be significant, in other words, a rifle round. He also noted that ballistic gel has no bone to deflect a round or clothing to clog up a hollow point.
Based on his observsations, the fiveseven is not a very effective round when stacked up against the same hit with a 40 or 45. It all comes down with shot placement with the fiveseven, which thankfully, with a little practice, is pretty easy to do. The fiveseven is a great gun, high capacity and light weight, two very important factors from a carry standpoint, and it has the accuracy to make it deadly, but hit for hit, a larger caliber would be prefered.
Now you know my reason for choosing the FNP45 Tactical. I understand it is one of the smoothest shooting 45's for followup shots and the high capacity doesn't hurt. I'm not sure I'd want to run a 5K marathon carrying the FNP, but for a fixed defensive area like the home, I think I'll end up chooing the FNP over the 5.7 but the 5.7 is probably going to stay the primary carry pistol.
Just to round out the discussion, for summer shorts weather I also carry a Walther PPK/S. This is by far the most "accurate" handgun I've ever had. It is a natural pointer with homing bullet capability. It's really funny because the gun is so small and the sight radious is so short, but I can plink gongs with it out to 100 yards with iron sights (once I figure the 3 foot drop at that range). One of the funny things is that the sights are right on, but about 1/16th off from center. The barrel must not be drilled straight in relation to the frame.
My other 'handgun' is interesting. I have a Rock River PDS. I'm not sure how this passed BATF as a handgun, it's basically a short barreled AR-15. It finely threads the line between a SBR and AOW, is legal as a handgun, and technically legal as a CCW. Not something I would normally "carry" but something that is nice to have when camping out in the boonies (where you can hear the strains of banjo music at night if you catch my drift). I used to have an 870 Express for this purpose but is was such a PITA to transport and it had to be cased an unloaded. The PDS can be transported uncased and loaded since it is a pistol. It has a picatinny top so I can run anything from iron sights to a Pulsar day/night vision scope. plus mags from 20 to 100 rounds. Very versitile.
Anyway, on the accuracy thing, the fiveseven seems to be at one end of the spectrum and the FNP Tactical at the other. It's going to be interesting to compare both. As Ripley said, "It's the only way to be sure".