Errol, thanks for helping me w/ this setup. U2 Ian.

The aircraft mentioned is the Kyosho Flip 3D.

**Ive checked the items that you've pointed out and here's what I've got...

My CG is at 165mm.

Plane weight is 4lbs-14oz using my buddy's digi fishing scale.

Elev halves are symetrically joined by the stock "U" joiner included in kit (bellcrank?).

Equal throw on ailerons in all directions (up,dn,L/R).

Coupled mixes are as follow:
mix 3) Rudder-Aileron, -15% (ail moves in opp direction to rud, both ways)
mix 4) Rudder-Elevator, +10% (elev moves in up direction to rudder both ways)
-No Elevator to anything is mixed.
-No Aileron to anything is mixed.
(I've double checked everything)

I don't quite understand your last question tho, "mechanically trimmed with a lot of bias?"

Do you think I should "point-mix" left aileron at about 80% of up-elev input?

I've been using the flap switch for spoileron/flapperon mix and have found myself fumbling around to find it w/ a few close calls. I called tech suport at Horizon and Dave told me that the sprung trainer switch was NOT assignable (bummer). I wonder if I could physically swap it out w/ the other position switch on the other side (the one that you referred to) to make it an assignable sprung switch? NEways, I like your mix switch idea a little better, for now and I think it'll be easier to find than the flap switch. Bummer about the sprung switch.