The only reason nvidia users are locked out from using free/adaptive sync is because of nvidia refusing to support it, they had an excuse with it for all pre 10xx desktop GPUs (as the GPUs didn't have the required hardware hence the need for them to build their own module), but not anymore.
Tom Peterson has said "never say never" with regards to it so it is only a matter of time especially when freesync monitors are dwarfing the number of gsync monitors out there:
http://www.pcworld.com/article/3129...ia-g-sync-on-monitor-selection-and-price.html
Superior option? For the range, sure, but everything else, not really as pointed out by tftcentral, anandtech and all the other good review sites (especially since AMD added support for LFC in a driver ages ago and most recently windowed support)
Just remember that regardless of sync tech., you really don't want to be dropping below 45 fps at most still.
UFOtest actually have a pretty good comparison tool to show of gsync and its effects on tearing, stutter/smoothness etc.:
https://www.testufo.com/#test=stutter&demo=gsync&foreground=FFFFFF&background=000000&max=12&pps=720
Of course as they mentioned, you can't get a feel for input lag etc. though.