Interesting thread.
Our locals used 5-minutes for the most recent event. (Players generally want to prep for EVO based on some polls we set out before the event.) Previous events used 6-minutes. I haven't done a thorough investigation on how long the matches actually took in either case (and there have been other changes recently, such as customs adoption, so it isn't a perfect comparison), but if anyone else feels like evaluating the data, the archives are available for viewing:
https://www.youtube.com/channel/UCmiYMlggo3KH2U4xI1NvhaQ
Personally, I don't think "5 minutes leads to more stalling" is a valid argument in any case, simply because I believe that playing for the clock should be a legitimate and respected strategy, and that tournament staff should always prepare for worst-case scenarios anyway.