EDC: SIG P938.
I've shot IDPA competition with 5", 4.25", and 3.5" pistols, and while I don't notice much difference in speed/accuracy when shooting the long and middle lengths - even though the Commander is a Lightweight - I find the short gun distinctly harder to shoot - even though it weighs five or six ounces more than the Commander.I probably should've clarified in my original post, my thoughts had little to do with velocity and more to do with sight radius. The difference in velocity between 4", 4.25", and a full size 5" barrel is likely not going to be much. 100 FPS tops, and at the ranges I shoot that's not enough difference to make a difference.
Where I do see some difference is with sight radius. The sight radius on the full size gun results in marginally better groups out to 25 yards. For practical defense shooting it's still not enough difference to make a difference though. And that gap could probably be closed with a little practice. I don't think it insurmountable.