Hi folks,
When I got into beekeeping I read so much, Pink Pages, M. Bush, etc.
I did go top entrance on a few. I just cut out the low edge on an inner cover. That, and generous dimensions of the outer telescoping cover resulted in successful upper entrance, somewhat protected from wind and weather.
Hives did well. I went this way on some hives for several years,... until I noticed the bees were sharpening their mandibles and chewing away the rabbet edge of whatever top box they were using. I'd still be using it if those chewed boxes could still have good box to box, or even super connections, but NNNOOOOOO!
I repaired with wood putty, wood strips, coffee cans, duct tape, Bondo,...
Freakin' Carpenter Bees! Ruination of perfectly good boxes.
Sal