Can you add the option to automatically reduce layer height for high "overhang" areas to 1/2, 1/3 or 1/4 of current layer. This only need to be done on areas where the angle more than a specified angle (say 30deg or so). This will allow for much smoother finishing yet allow maximum speed on sections that do not need the higher resolution.
Using different processes do help in this regard but then the whole section of the model need to be printed that way slowing things down. Also using different processes one need to find & define the ranges manually. The interfaces between layers also tend to be printed with 100% infill (or one might get areas without infill where you wanted it).
I sometimes create the zones with overlap & then go in and delete the overlap area manually - a bit tedious if you have a lot of these zones with overhang.