quaker1

I think what he means by gear drive is not a geared motor drive on the tail like most standard micros but a tail rotor that is driven off the main motor by means of a driveshaft. The benefit of this is if you have a fast servo controlling the tail pitch its far more stable and responsive than a seperate motor driven tail could ever be.
Plus a shaft driven tail has the ability to push in both directions which is handy if you were to cut the throttle quickly, which would normaly cause the heli to rotate clockwise. A fixed pitch tail rotor can do nothing to stop this whereas a shaft driven with adjustable pitch can push in the other direction and stop this from happening.
The main dissadvantage with a driveshaft is the risk of damaging the shaft, boom and gear assembly if you have a crash, the other is more robust.