RE: Synergy or Adreniline?
I think the synergy will be nose heavy. I had the YS 110 on mine and the battery had to be behine the te of the wing.
As for size, bigger planes do as a rule fly better. I have a Kyosho Cap 40 with a YS 63 and a seduction with a YS 63 and have not touched them since I went to bigger planes. Only exception being the Madness.
Cheers
Kris