omnificI don't see how this would be beneficial to your gameplay in the long run, cuz at the end of the day you're still playing on ESEA's servers for your matches, which run at 66 tick.
Doesn't apply to EU/AU/UGC. I think this is very interesting and hopefully there aren't any nasty bugs that come with it.
EDIT:
It looks like the cmdrate/updaterate is capped to 100 so the max tickrate a server can use is 100. Maybe there's a way around this cap.
Doors open/close much more slowly. This is very game breaking, because as a scout you have to wait 0.5 seconds for a door to open in Badlands, and rockets goes through roller doors that haven't properly closed yet.
It seems that ctap rocket jumps are slightly better with high tickrate (or maybe just easier).