Could never get enough power for electrics on my Trex 550 12s. Servos would run spongy and would trip low power warnings under hard pitch pumps. Tried many different BECs and receiver batteries with no luck. This one worked awesome because it is small and powerful and give you the option to run a backup battery to it. I think that this works better than the castle for the money. The only downside is you need a 3s or higher battery to make it work, most BEC usually run off of 2s.