"is the .45acp a better manstopper?" all HG cartriges, of course, are underpowered for 1 shot stops on people (now that is outta the way)....i believe that with the right loads (JHPs) that expand consitantly will work fine on people
as to caliber--9mm-45acps and the .357mag would be the ideal, fast-shooting, antipersonal HG cartriges (the .357mag has an edge over both the .45acp and 9mm and is rated as the #1 man stopper by a lot of 'studies')
personally, i go w/ the .45acp; almost anyone can agree that the wider the bullet (w/ adequate penetration), the higher your chances of it damaging something vital--pick the biggest, most comfortable shooting cargtrige/gun you can shoot
shot placement IS everything, h/w, there are other factors to consider imo...such as body size, mussle mass, clothing (material, thickness, etc), jewlery, drugs (natural/unnatural) that may give someone an 'edge', etc that factor in an oponenent;
then there is the bullet itself--NO JHP can guarrentee a 100% expansion rate, expecially through crap in the way of your vital targets
"a 9mm MIGHT expand, but a .45acp will NEVER shrink"
h/w, thats just me; as to ammo capacity, i just carry more mags
i dont carry a .357mag only b/c there are no practical sized ones in an auto, and revolvers dont carry enough for me; i dont like shooting the .40sw; the .357sig, while nice shooting is a tad harder to find ammo locally; 9mm--cheap, easy to get, hi-cap, etc is great for practice
.45acp--love shooting it, avaialble, more energy, less chamber pressure than .40sw, not usually potrayed as a "poor manstopper"
regardless, its a gun/ammo combo that will work whenever, 100% of the time that will be the best
a G26 would be fine