Hello Grahm,
The Maximum input voltage to the AQ is 18 vdc.
If you dropped the voltage below 18 vdc you would lose the voltage adjustment properties of the controller to changing power output and the low voltage sensing abilities. A six cell battery at 3.1 would still be above max input.
V1 and V2 boards have the same max voltage limitations.
You could change the Recoms to ones that handle up to 32vdc but they have a reduced current output of 1amp. That should only present a problem on the one that provides power to servo's and esc's if trying to run a gimbal. This should normally be run by a BEC anyway.
If you are in the US I would think you are fine with a DX8 on one satelite as the US transmitters have more power output. If I fly a ship on long missions I do use a MK diversity board. I power it from the AQ 5 vdc and let the regulator on the board power multiple satelites. I sometimes use a good Spektrum satelite and throw on a cheap HK clone as the backup.
I've built my own copies of the diversity board but you can buy them here.
http://www.nghobbies.com/cart/index.php ... cts_id=718