I like the idea of switching my 1080 ti to one of those 2080 supers... Looks nice...
Why? It's basically the same card with slightly higher clocks and RTX, which it's not even powerful enough to use adequately. Gamers Nexus review of the 2080 Super is pretty spot on.
From a performance stand point, nothing short of a 2080Ti really makes sense if you already own a 1080Ti.