RE: plane rolls with elevator
Maybe I can add some further info
He's a Mode 1 Flyer (elevator & rudder on the Left Stick) - One of only 3 that I've encountered here in Texas (When he came to visit me early this year).
The Elevator system on this model (Black Horse Super Air with an MDS 48 & 11/5 Prop) is from a single servo but with separate push rods (wire enclosed in a tube) to each elevator half (& a connecting block joining those two rods just prior to the servo). He's checked that both elevator halves are moving the same amount from neutral. I've also had him check the Lateral balance and to operate each channel at a time with the engine running on the ground to see if there is any interference to other control surfaces - all appears to be OK.
I haven't actually seen the model do this (He's in Australia - I'm in the US) so I suggested to him to post his query here to see what suggesstions he gets.