Anecdote and small sample size alert, but since I've used both versions (albeit in the slick model), I figure it might be useful to relay my experience.
After getting a few punctures on my tubeless Gravelking slicks, I swapped to the puncture resistant version and almost immediately got a flat from glass. I was using tubes, so maybe tubeless would have rolled over the glass without an issue, and maybe it was just a rash of bad luck, but I don't think they're appreciably tougher than the normal version tire. I rode the same stretch on Conti 4-Seasons for years without many flats, and would switch back if they were available in > 32mm width.
I don't know if the SK would change the math, my guess is that it's probably a similar layer of protection in the SK and the slick, compared to the normal versions of each. If you can find them for the same price, sure, the tiny weight increase is probably worth it, but if puncture protection is a concern where you ride you might want to consider another tire entirely.