I think that each model equipped with a mercury can have different result, regarding the flight behaviour with flaps.
Here is my experience with flaps of an Avanti equipped with a mercury SRS V09, and the behaviour was the same with the V07.
In assist mode:
- middle flaps (take off position) without any mixing: no trouble,
- full flaps + "aileron in airbrake" (landing position) without any mixing: strange behaviour. Sometimes perfect, sometimes while in turn or while speed is reducing I can see some strange pitch manoeuver and I DO not want to see these manoeuvers during my final approach. (and I can't modify the elevator gain: if lowered I don't have the knife edge corrections, if increased I have oscillations in normal flights)
- full flaps + "aileron in airbrake" (landing) WITH elevator mixing: no trouble but I'm aware that I don't have the "assist mode" advantage, as my elevator is far from initial center position.
I don't have any ballooning during landing, either without gyro, or with rate mode or with assist mode, and with or without mixing.
My positions are:
FM1: NO GYRO
FM2: ASSIST 45% aileron+ elevator, RATE 45%, for rudder, vector thrust disabled
FM3: RATE 45% FOR ALL; vector thrust at 100%
My chrono flight is:
- just before take off (to have all surfaces at 0): FM1
- take off , all standard aerobatics and landing (with flaps to elevator mixing): FM2
- hovering or spin or funny manoeuvers: FM3 (I can also land with this position as the elevator mixing is always active with flaps)
- any suspicious manoeuver or doubt on gyro: FM1
After some test I finally had the same gains between the V07 and the V09.
I'm currently using only SOFT behaviour but I think that I will increase a bit the vector thrust behaviour to NORMAL or more, as the Avanti feels unstable in harrier.
I hope this helps.