I have some some useing the "diablotin setup" B50 13s 6.7:1 14cells 18x8 prop. Most of which now run on 4s4p TP or so. I would expect 6-8min flights on 14xGP3300
check this video, from RCcraze. a heavier setup but good performer.
http://www.rccraze.com/flip.mpg
/Henke