Palgia, just throwing a new hat in the ring......
IGE,reduction of ID will allow a reduction in incidence to maintain a particular height; for a prop. a/c this will probably result in a small reduction in the asymmetric turning moment(downgoing-blade effect),but probably little effect on rudder yawing ability at full deflection.So, it is possible to reduce speed a little until one is again balanced ,ie incidence again increased at lower speed to maintain ht. and asymmetric thrust again balanced by full rudder. Can`t confirm as yet as I am trying to get hold of a certification TP....I`ll also ask about effect on jets as well.......