I think the right balance will differ from person to person and I certainly wouldn't advise anyone to shoot a really high comb, but just high enough that the eye stays a little above the rib will definitely help most people to prevent head lifting.
All things being equal a flat rib picture will at best throw a 50/50 pattern so one that is a tad higher should only throw a touch higher and in no way lead to any need to factor in a shift in POI, in fact on birds such as Teal or tower incomers it would be an aid, in essence the main advantage is better all round vision (which lasts throughout the execution of the shot).
As with every set up once you settle down and shoot it a while the mind soon learns how the pattern/sight picture interact.
All things being equal a flat rib picture will at best throw a 50/50 pattern so one that is a tad higher should only throw a touch higher and in no way lead to any need to factor in a shift in POI, in fact on birds such as Teal or tower incomers it would be an aid, in essence the main advantage is better all round vision (which lasts throughout the execution of the shot).
As with every set up once you settle down and shoot it a while the mind soon learns how the pattern/sight picture interact.