[BrianG]

Serum: yeah really! Where are my priorities!? :)

Griffin: I couldn't find an exact part number match, but I did find a partial match and when I looked at the package, it was a transistor. So, I suppose I should have dug further. My bad. :dft001:. And even then, unless the LDO regulator IC specifically has FET outputs, you shouldn't parallel them. In this case, I wouldv'e used a pass transistor to boost the current.

HOWEVER! I did some testing that should really "put the nail in the coffin" for the argument to disable the ESC's BEC. Using several resistors, I hooked up a small 250mA load to the 5v output of the ESC BEC.

On 2s, the regulator circuit got warm, ~100*F, and seemed to hold that temp.
On 3s, the regulator circuit got very warm quickly to around 140*F within 20 seconds.
On 4s, the regulator circuit got very very warm very quickly to over 160*F within 20 seconds.

Don't forget, the MM uses the PCB traces as a heatsink. So, all that heat warming up all the surrounding components on the "brains" board. I don't what USB controller or motor controller ICs they use, but I highly doubt they are meant to handle that kind of heat. And these devices aren't even on a heatsink.

So, the lesson learned here is:

ANYTHING over 2s, use an external UBEC.