I've known a few 9mm guys that claim if limited to just 10 rounds you "might as well go with 10 big rounds." Personally I don't necessarily agree. The 9mm is still easier to shoot well and easier to shoot quickly. It recoils a lot less and allows the gun to be smaller. No single stack 1911 in .45 ACP can fit 10 rounds (unless you find one that sticks out the bottom 1/2") so you're still comparing a relatively svelte 10 round 9mm vs a larger .45 ACP. But I guess it would at least give me an excuse to get an HK45!