In order to get good finish and precision in near horizontal surfaces, you need to slice the entire model using a small layer thickness which results in low printing speeds.
There are many cases where one has to print with 0.1 mm layer height just to capture a small percentage of the features of the entire model, while everything else could be printed using 0.3 mm layer height.
My proposal is the implementation of local adaptive slicing. It should print with different layer heights based on the slope of the features. Vertical sections of the model are printed with maximum layer height and near horizontal surfaces with low layer heights resulting in better finish and precision while maintaining maximum printing speed.
A quick Google search revealed that work has been done on the subject a while ago: http://utwired.engr.utexas.edu/lff/symp ... Tyberg.pdf
There are illustrations in the document that describe the problem and solution way better than I could with words here.
I believe it should be relatively easy to implement and, at the same time, a big leap in printing speed and quality.