John I, think you should be more worried about balance and carrying dead weight rather then flight times but although i dont have the 5 in 1 unit 2 ground runs and 1 4min flight i put about 150mah per pack for the rx, I cant imagine the 5 in 1 would be too much extra on that maybe 50 mah per flight, so based on that and having 1 2600 mah rx pack id say youd be right for a bout 4 flights before pushing your luck. If you have the 1/8 f16 then dont worry, reading this thread i think nearly everyones has come out tail heavy and most have used batteries in the nose for the weight. Me I have 2 5200 lithium ions for the rx and a 2600 lithium ion for the ecu and even then i had to add 40grams to the nose, hope this helps</p>