I've seen that same finish loss on many of my Sigs, and to varying degree on groups of 229, 226 and others. Some seem to wear in a bit more than others, but then once the wear pattern is established it does not seem to get any worse. Tight tolerances, tight lockup, solid pistols. I would not refinish that and just shoot it.
I love my old Rugers, "ruger rough" is a thing to be sure. Even so, clunky, rough, but they've run just fine. Many thousands of lead cast reloads, in various guns, and they still run fine. No question the fit and finish of Sigs is superior, but when I started out I could afford Rugers. Now, I still don't buy "high end" Sigs or others but tend to buy more utilitarian models. I've been up to Sig many times, and dealt with customer service there and had no issues at all.