That's true at stock, but once you increase the power limit by about 30% you just start running into the voltage limit. At least that's the case with my 2080 Ti (could be different with 2080S I suppose, but I doubt it). At 130% power limit I'm basically either limited by voltage, or by both voltage and power (at least according to the MSI Afterburner Overlay). So having a super high power limit eventually just means you're capped by voltage. Sure, I could flash my card to a higher power limit bios, but there's not much point if I'm just voltage limited almost all the time anyway.
In addition, there's also the issue that there are serious diminishing returns the higher frequency goes. That's why, even when you're power limited, you're generally only losing about 100 MHz of clock speed anyway, or maybe 150 MHz at the outside. That's certainly not nothing, but at clock speeds close to 2 GHz, it's also not going to account for more than about 5% more performance.
Given all that it, seems to me that even with no power limit, water cooled so less temperature throttling, etc, a 2080 Super, at best, might match a non-A 2080 Ti at stock. And in reality I expect the non-A Ti to still be 5-10% faster since performance doesn't scale perfectly with core speed (memory limitations). On top of that the non-A Ti can also have its power limit increased by 12%, as well.
When you consider that a water cooled 2080S is probably going to set you back $100-$150 more than a standard 2080S, I just don't see it as a good buy. I'd rather just get a 2080S with standard cooler for less, or get a 2070S and push it to 2080S speeds via water cooling. Just my personal opinion.
Of course, if someone already owns a custom water cooling setup with a GPU block that can be directly transferred over, then maybe the calculation is a bit different.
