Those of us who use either a Sig or an XD in competition are in a definite minority. So not exactly a poll, more of a discussion area on what modifications work for you, what you've tried, what didn't work and your overall impressions of how your Sig(s) or XD(s) work for you in comparison to other guns you've tried.
Right now I'm back to my XD in .40 after a year with a 9mm Sig 226. All I did to the Sig was to swap out the sights for fiber optics front and rear and put on Hogue fingergroove grips.
On the XD I use Springer trigger parts and similar dual green fiber optics on the rear with a red fiber optic front and have added an Agrip wrap over the factory plastic grip.
Either gun feels better in my hand than a 1911 (single stack or fat gun), due mostly to having large but relatively slim hands. The XD seems to be faster on followup shots with similar power factor ammo as the Sig has a pronounced bounce on firing that is less evident with the XD.
All that said, I'm working on a Caspian single stack 9 for next year and hope to find the right combination of components to enjoy shooting a 1911 for one more year of competition before I hang up my guns.