Convetional rotorcrafts are hard to hover as when we increase collective, even tail rotor pitch needs to be compensated. But in coaxial design, will just increasing the collective do the job as torque doesn't change?
There is more than just compensating the tail rotor pitch (which I believe is somewhat compensated for anyways mechanically), which makes hovering a single-rotor helicopter challenging. You also need to tilt the main-rotor to compensate for the side thrust of the tail. If the main rotor is vertical you drift sideways.
However, keep in minds rotors are never perfectly identical. So you still need to compensate manually, if even a very small (possibly unconscious) amount.
I don't know if it's hard on a coaxial, but it should definitely be easier than on a single-rotor.