Hi jjuk.
My 500x with Spirit2 is down at the moment, but will post detailed fbl-settings when up and running in a few weeks.

My basic experiences on trex 500x with 85mm tail blades and max collective +/- 11 degrees is as follows:

My mechanical tail adjustments:
Rudder servo arm 14mm from center servo to center ball. Tail mechanics so smoothe that tail pitcher falls down by gravity when pitch arm disconnected and heli layed down on left side. Tail rod length adjusted until heli dont turn left or right when hovering in tail gyro mode normal (tail gyro gain switched to negative/normal -50% when hover with throttle 60%)

Idle 1 - takeoff/landing:
50% throttle, barely enough power for pitch pumps, hence tail kickout is not a big deal. Anyways, tail gyro gain positive/headlock 50-60% worked for me. I also needed some revomix, increased from zero in small steps until tailkicks where gone.

Idle 2- eco 3D:
60% throttle, tail gyro gain positive/headlock 50% worked for me. I also needed some revomix, increased from zero in small steps until tailkicks where gone, less value than for Idle 1

Idle 3- 3D:
90% throttle (I leave 10% headroom for governor in Hobbywing esc), tail gyro gain positive/headlock 32% worked for me. I also use some very little revomix allthough not necessary, tail straightens out perfectly on headspeeds 70-90% throttle anyways.