My primary pistol for both USPSA production and SSP for a bunch of years was a stock 226R with an alloy elite frame. I bought a stainless 226 elite a couple years ago, interested in what the heavier gun would offer. I went back and forth between the two a lot. The latter has a Gray action job that was done by the previous owner. The alloy pistol is a high round count gun with lots of mileage (40K+) on the action parts (and at least double that in dry fire), but no action job; just very well worn in.
I have Heinie fiber fronts and plain black (charger) rears on both. I use stippled stock grips (my own doing) and run 19 lb hammer springs. I use 11 lb Wolf recoil springs for use with my production load (130 PF) and I try and stay on top of regular replacement. Both are bone stock otherwise.
I made Master in production about a year and a half ago shooting the stock alloy gun. My initial plan was to treat myself with a more well accepted competition specific production gun (Tanfo, CZ, etc.) but I've stayed true to the classic Sigs. Mostly b/c they're what I carry for work, but also b/c they're just excessively familiar. And I'm a bit anal with regard to that I guess, for better or for worse.
What I did do, as a bit of a middle ground, was purchase an X5 Allround I came across. It has an action job from a pretty well known 1911 smith and it leaves me giggly every time I shoot it. The SA is on par quality-wise with a well tuned 1911 trigger. I've been shooting it in USPSA for the last half a season and plan to continue to do so. It's sick!
But alas, I can't really do anything with it I couldn't do with the stock gun.
Hope that helps.