I think if you move your CG back up to at least the 150mm mark, the snapping will subside quite a bit if not altoghther. The spec is 120 to 150mm and I find that, at the 150mm spec, with a close to empty tank and the big Saito 100 still pulling at idle, the landings ballon quite a bit and in flight almost no down elevator is required to hold inverted straight and level flight on a full tank. It hovers and tumbles great and everything else with the exception of the KE coupling couldn't perform better. If you move it all the way up to the 120mm mark, it can almost do IMAC type routines on low rates with some precision. Notice the disclaimers in that sentence. IMO your CG is whats causing your snap. It may also be exagerating the wing wobble in stall moves like elevators and harriers.

Your weight is no problem. Yeah, thats what I call the bellcrank. Probably not the right term. Your mix 3 and 4 percentages may change with the CG shift. On your MIX 3 and MIX 4, are they switched or always on? If they are switched then you can just make them on all the time as you will likely need them in all rudder corrections and they don't affect the hover very much if even noticably around the 4 - 8% level that I have to use. The Prog Mix switch is a lot easier to find in flight for me being right behind the rudder DR switch so I put that MIX 1 ELEV+FLAP mix switched there. I switch it off for snap rolls, blenders and flatspins and any other move I feel it is adversly affecting although those are the only ones I have found so far.

By "mechanically trimmed with a lot of bias" I would be asking if after your first trim flight, you had to trim a control surface with the pushrods a long way from it's visual center due to needing a lot of trim in flight. It is always best to mechanically trim the plane after the first up to even the fifth flight if necessary to keep the electronic trims at or a click (Beep) or two off center. Something like a rudder pointing off center to the right control dirrection or ailerons adjusted with right roll bias for straight level flight would be a first place to look. This doesn't seem like it will be your problem with the snap but look it over. That snap should be nonexistant on that plane at that weight if the CG gets back forward and you are not flying such inputs at full speed. even at full speed it should fold the wing before it snaps. My first Flip did that but I was doing a wall at full speed, my fault. If you want to point mix the Left aileron for the snap to the right, You should not need it once the CG is back forward 15 - 20mm. The snap has to go. I hate the snap and this plane should have almost none if any.

BTW where did you get 165mm for your CG? Just curious. Must be a handfull to fly and land.