I own a lot of SIGs, and I can't say I really think that SIGs have more muzzle flip for a given cartridge and barrel length than any comparable gun I have fired. As for competition, my SIG P220 SAO has done right well by me in IDPA so far.
I think muzzle flip has a lot more to do with stance, grip, technique, and ergonomics to the shooter than a small difference in bore axis in most standard calibers. I am slower with follow-up shots on a Glock, I think (and this is just a feeling because I haven't compared times with a shot timer), because the grip angle means my natural point-of-aim with one is different, so I find it harder to get the gun to come back down to the original geometry after the first shot. For my SIGs, though, the return to aim is pretty much spot on.
Now, if we were talking .44 Magnum out of a 2--3 inch barrel, then I think we might start seeing some noticeable differences in splits based solely on barrel height...