If you have the time for 2½ hours I would always go for it, the 15 minutes more per player are defenetly smth. I guess it's also just a matter of how used you are to play on a tight schedule. More gametimemeans either less space in between games (for breaks/big eating break, Organisation, pairings, etc) but if the TO and all Programms run nice and smoothly, that should work quite well. Or the day is bit longer. As said, you have the option and time, go for longer games. Slow players will still find it challenging I imagine. There are quite good apps for everyone to download for free on their smartphones.
