Locking CG is a must and it is very personal thing. I'll give you that.

I haven't flown Hawk with iGyro so I can't comment on that. It inherited old Cortex from earlier plane. I don't know if it has partial HH in rate mode or not. Same setup actually has flown in both of my Hawks. There still seems to be a lot of things I can't explain in accurate terms when speaking about "feel". I'm still trying to find it after radio has changed from Futaba to Jeti. Expo is totally different and propably gyro gain is altered also.

Two experiences agains HH mode I have gained from Cortex non-pro and iGyro3e.
- Planes that don't have "pure" inputs like F-15 cortex used to fly with: don't use HH mode in rudder. It takes only seconds to find yourself on knife-edge snap or something after enabling HH. However this shouldn't be the case on Hawk. It has very rudder and small coupling to other controls if balanced right. But this is CG related thing. It is no way near one hand knife-edge capable if weighted forward. So be carefull with it.

- To me it's somewhat impossible to fly slow roll without elevator and rudder correction. HH mode is active only when one control is moved like you said. Corrections are very hard to unlearn to do. I have tried to lear this with my M346 Master that has i3e and has lots of coupling. IGyro is not able to hold dart like slow roll even on HH mode. It has good consistence but I bet I can do better slow roll by myself. HH doesn't hold tendency of gaining altitude when advansing throttle either. Here thust angle correction is something like 20 to 400mm. Gains can be low if they need to be very different on HH mode compare to Rate mode dunno. On landing approach HH ok but there is still big jump to learn not to make corrections. I gues this is that artificial feel I mentioned. If there is a jump to learn how elevator and throttle switch places on slow approach. I'd compare it to be equal to learn how to approach in HH mode and not make corrections.

/Jyri