I do suggest buying an OPTO version on anything over ~30 amps. However, I would use a UBEC in place of the RX pack. You can just see the UBEC in my first post as it sits just above the RX (white shrink wrap). You can probably get away with using a BEC version, but it is just on the outer limits of the BEC rating. That is another reason why I like Castlecreations Pheonix controllers. You have the option of using the BEC or disabling it by pulling the center (red) pin out of the plug.

-Mike