After getting a VKB Modern Combat Grip, which is heavily based on that of the SU-57 and SU-35 (and similar to the SU-27S), I was very intrigued to see that the two-stage trigger is labelled 'AP DISENGAGE'.
Seems that this trigger will disengage the autopilot (duh), while the flip down trigger is used for weapons.
Does this mean that the doctrine is to fly most of the time in attitude or altitude hold, and to hold the trigger down to manoeuvre? This would obviate the need for constant trimming that people seem to complain about.
I gave it a go and found it pretty unintuitive at first, may have another crack at it in future.