[Cain]

For me at least, unfortunately RC Pro series rules for me only allow 4S.

From my understanding:

14.8V 8000mah = 118.4 Whr
22.2V 5000mah = 111.0 Whr

very close though as theoretically on my calculations (could be wrong here), assuming 25 minute run with the 8000mah packs, should see about a 2 min drop for the 5000mah, not taking into any account efficiencies with more voltage.