Keep in mind that I am shooting SASS, not NCOWS (yet). Rough estimates here, but...
1/3 or so shooting Rugers. Mostly .38's. A few .32's or .45's.
1/3 or so shooting Colt repros, more Ubertis than Piettas around here. Most of those repros are Pre-War. Still mostly .38 but a higher percentage of .44's and .45's than the Ruger guys.
Of the remaining less than 1/3 are the opentops and conversions, schofields, Remingtons, percussion guns with conversion cylinders, etc. Lots of calibers.
And oh yeah, maybe 5% shooting real Colts. Pre-War of course
Personally I have not seen an Uberti with the new firing pin at a match, although if someone showed up with a new Uberti I'd probably have no idea. Keep in mind that these have only been out around a year. There have been a few issues I've heard about, but mostly they work fine. But like you, I really don't want one, either.