8.4V?

There are no 8.4V lipos, but I think your referring to a 7.4V 2 cell lipo. In which case, I would move up to a 3 cell with the Reflection. It really needs the extra voltage. Its a tad on the heavy side, so you need the extra umph of a 3 cell (11.1V) lipo to get it to perform correctly.

Bill, I flew my reflection today. Not a bad little airplane. Ive got some trimming to do, the rolling circles arent quite dialed in yet, but its really close.
I dont like that "no aileron/elevator" turn thing. Reminds me of a tensor. Rudder is SUPER sensitive, Ill dial more expo in it. KE loops are amazing. It will KE loop in a real tight space. There is some rudder/aileron coupling that I have to work out of it.
I figured I would have to really tune everything to get it to fly right, and get everything dialed in.

This is definatly a plane where you have to adjust things to get it to fly right. Darn shame they made all the linkages where you CA them in place. Now you cant adjust them. I swapped my aileron linkages out for IKARUS shocky style links. This way I can adjust the linkages on the ailerons.

Plane flys pretty good, it just needs alot of tweaking.