thats what im doing too, i use the skookum power bus to feed all my servos with 8.4 volts then its just the signal pins in use on my beastx. im running outrage torq all round though. no regs needed, 2700mah lipo straight to my powerbus which feeds the servos and the beastx. the second output from my 2s lipo feeds my ar7000 rx.
the other big advantage of doing things this way it that there isnt large clusters of wires going in to the fbl unit carrying vibrations with them