My phantom is still in the hangar, but its new goodies are in customs now, so soon I'll be flying again. Its a Phantom 1.2 and I will have tmotors, vision props, 600mw fatshark, Arris 3000. Decision on gear is not made yet. My guess is that with current self made gear and stock battery, Gopro3 weight will be around 1230 gram. A second battery would make it around 1400 gram, probably too heavy, more wear and only slightly increased flight time. Been looking around a bit and found a zippy battery of 1500mah weighing just 108 gram. (and 9 US$ only) So two of them would be just 46 grams heavier as one stock. So, total weight would be 1230 + 46 + dual battery mount would be < 1300 grams with 3000 mah on board. Would that work?