I shot a film last year and persuaded production to go Super 35, 3 perf, 1 :185.
It is an enormous cost saving ( 33%, NOT 25% ) and great for the DP as no one can try and compromise your frame later for TV. Director's happy too as it takes some stock pressure away.
Sadly, many producers still don't understand it, and reject it as it seems unusual. They'll figure it out soon I'm sure.