Guys, thank you all for the suggestions.

Anyhow, my foamy is a bit different. I set it up for a pattern style flying, not 3D. I used 3M scotch as my hinges, and it works really GREAT. No single corner has detached since when I put it. Regarding elevator linkage histeresys, I have to check but it is definitely out of consideration: hinge is solid and my elevator has 10° of throw! CG is well forward: I have a mix for hands off downlines, otherwise a pitch to the canopy will occur - well forward the neutral point I guess!

The strange fact is that it has absolutely no play, it flexs a little due to the thin linkage, but no free play. That linkage is the best I have on my plane! My ailerons have some amount of play, the rudder also, but the elevator is absolutely ok. I was surprised when I saw that the elev servo didn't have any play! I've been lucky here!

Anyhow I'm speaking about very small trim differences: I put it hands off at half throttle at the beginning of the field, and I watch it flying for several dozens of meters...

Perhaps am I demanding too much? [&:] I'm a pattern guy...