Most tail rotor assemblies have a hover OFFSET (pitch) built into the blade grip to slider linkage ... so with the t/r rotor input at neutral and trim and subtrim centered, you will be producing the necessary pitch to hover (assuming you've set your heli up to match this built in pitch).

Of course, this hover OFFSET will only work at hover. The moment you change this (collective pitch change, RPM change, etc), the main rotor to fuse torque differential will change and then the hover OFFSET will not be sufficient ... the heli will YAW.

Some "system" must be in place to control the YAW ... assuming the pilot doesn't want the heli to go spinning roundy roundy.

The first very basic system is the pilot him/herself. Just move the t/r stick to correct for the YAW change. Ok, it may not be the best system but it's certainly do able.

The second is you can program some REVO to "kinda" correct for the change. REVO is just a mix that adds a little (or alot depending on your programming) t/r adjustment based on where the t/r stick is. So it adds the necessary t/r movement as you move away from hover (either up or down). The only problem is that it's a mix in the TX and has no clue what the forces are actually at the heli. A YAW control system onboard the heli would be better ...

The third is the gyro itself. In Heading Hold, the gyro itself would hold the YAW on the heli so you as a pilot can move the collective stick all around and not worry that there are torque changes ... the gyro will deal with it and while in Heading Hold will control the YAW.

Good Luck,
d.tipton