Hi Dave,
James is right. Whatever tendency the rudder causes in knife-edge will be there in wings-level flight also. The mix will actually assist in decreasing the workload in a flat turn rather than increasing it. As far as hovering, the elevator moves so little in a mixed condition that it should be completely unoticable.

Getting deeper into the subect of mixology, if you are using a radio that allows multi-point mixing and have lots of patience, then you can customize that mix for different percentages at different rudder deflections (and even throttle settings) and create a complex mix that allows perfect knife-edge loops without doing anything other than pushing throttle and rudder. Me, I have never mixed one up like that but I have seen it done.

Mark