ORIGINAL: Lomcevak Duck
The short answer is no. Most aircraft do not tend to roll badly with rudder input while in a hover, even if they have signifigant roll coupling in level flight. And no, I can't explain that one.
Second, it depends on your plane in particular whether the rudder shape will cause it to roll with rudder input. There are several other factors that influence that, and your rudder's shape may actually be designed to negate that. Some other factors that influence roll coupling are wing placement (high, low, mid) dihedral, horizontal stab placement, verticle stab and rudder placement in relation to the datum line, as well as the rudder's geometric shape. By the way, what plane is it?
The wing is not loaded in hover. It's the only reason why the model or full scale plane will allow the engine torque to roll the crate
In my experience the rudder shape (of reasonable size and configuration) plays practically no role. Other model parameters as you noted (namely wing design and placement and dihedral angle) play the biggest role. Stab location vertically on the fuse also plays a very, very minor role.... vertical movement would need to be extreme to really show any effect on most low-mid wing planes
MattK