Regarding the electronics being fed from one of the ESC's BEC -
I'm on the way of making things very reliable.
I thought of feeding the tronics with regulated 5v, coming from a stand alone circuitry, 5v regulator off the battery.
that way im not dependent on a random ESC if it decides to blow...
of course it will be well regulated and decoupled.
what do you think of it ?