Lissart,
On the Cessna CJ's you certainly notice a difference when rotating with a coating of De-ice/Anti-ice fluid covering the surfaces - this was admirably demonstrated on a recent LPC by myself, will admit i'd noticed it (the relatively speaking extra force required on rotation) and hadn't made the mental link and it wasn't until the CRE/CRI i was with asked if i'd noticed anything 'on rotation' that the penny dropped ! In answer, certainly on the CJ's this is due to the relatively low rotation speed being around the speed at which the fluid would normally start to shear and the bulk leave the airframe.
Hope my basic understanding of this is of help, all previous comments also seem to apply but thought i'd add my specific case.
F/O