The PureHead has a low gear reduction (1:4.5). This works very good for most application. But due to this low reduction, the PureHead will not provide high torque.
So this will mean, that you will not be able to setup your camera off-center, like for nodel-point shooting for panoramas. You could tweek around by using counterweights, but otherwise you should keep the camera always centered.
If you are planning to shoot with high focal length, so also might want to consider a different solution. The low gear reduction will result in a low resolution. But this can be ignored for most cases, since the drivers in the PureControl will interpolate the movement and make it smooth as possible.