Ask a bunch of bee keepers and get about 15 different answers
So for my two cents, I would just go with a top entrance and close up the bottom entrance. I have hives that run the gamut of entrance configurations; top or bottom or middle. No matter which, I only keep one entrance open. The bees are perfectly capable of keeping the bottom of their hive clean with only a middle or top entrance. They just drag the dead up and drop them outside the door. As Brian says, less beading with a top or middle entrance.