Hi Zeeb,
If you want to run two lithium batteries you might consider our SuperReg rather than using the Batshare plus a regulator. This unit is compact, light and saves you extra wires. You will need to make Deans to R/C plug adapters to plug into your receiver (we have the parts). This might be a cleaner way to go.

The power on all receivers I know of is bussed across the unit so you can plug a power input into any open slot. In fact, the new PowerExpander II coming out later this year does not plug into the battery input of a receiver at all unless it is shared with a channel. The power goes in through the two channels at either end of the receiver.

You can use one output only of the BatShare but you will have more voltage drop across the single wire and connector. Two connections will give you a higher voltage into the receiver under load and thus you will get more torque out of your servos.

Please let me know if I can answer any more questions.