Started with an OS 46FX and have a OS 50SX on it now. Current prop is a 11 x 7 MA but am playing with a bunch of different ones now. Changing props sure does make a difference on this thing. The the 11 x 7 MA the verticals were vertical, knife edge required no corrections (even in a loop), and down lines pulled slightly to the canopy. Changing to APC's threw all the above out the window. I'm going o find the best setup if it wears the plane out.
That said, the Saito 100 should turn it into a rocket, if you prop it right and I don't think you will run out of vertical, maybe fuel tho.
You should be able to balance without having to add any weight just by moving the battery around.
Good luck,
Ed M.