Trex 250 build update

So. I pulled the MSH Brain off my 550 to test fit on the 250. It's too wide to go between the frames where the 3gx would mount. I guess I'll need to mount it on the side of the frame.  It would look weird with this box hanging off one side though :(.  I guess I could pull the 3gx off my 450 and put it on the 250 and the Brain on the 450?  The CG would probably work out better with the 3gx mounted in the right spot. 

I also pulled the Castle Phoenix 25 out of my Blade CP, since I was considering using it for the 250.  But now I'm worried that the BEC might be too weak?  Maybe I'll go with a Talon 15, which has a bigger BEC. Hmmm.