I bought a SCGC OO off eBay a few months ago and got a surprise when I opened the case seeing divots in the first nine frets. The divots were bad enough to affect intonation and my ability to properly fix the action. Normally I’d ask the seller to take back a guitar under such circumstances but instead I had it re-fretted.
I asked the same questions you did and eventually, with a little knot of worry in my stomach, got it re-fretted with stainless steel. The folks who did it were huge proponents of SS and convinced me to do it.
Some people had voiced concern that SS imparts a “ping” or a “zing” to notes when fretted, others do not hear this. I do not hear this. In my own case I feel I made the right decision and the tone of this guitar not did not decline, but is in fact better than before.
I cannot address the core of your question as completely as I’d like since I’ve only done this recently. I notice zero wear at this point. For comparison, one of my other guitars, a Martin 00-28, now shows just a tiny bit of fret wear and I have not played it significantly more than the SCGC. Once it’s to the point where it has divots it’s getting SS too.
Santa Cruz 00 — Goodall 000 — Martin 00-28