islandflyer ....
This is just my opinion....all your ideas are fine....but,
I would use a smaller battery in the 40 size, the retracts will add a higher
wing loading....and you want to keep that to a minimum. The flaps would
be cool on the XL, not cool on the .40....again, more unwanted weight on
the 40. I still use nicads....
Put a Jett .90 in the XL, and have a big and little Brother....
FBD.