I agree that it is very location specific. I no longer use top entrances due to very high heat loss up here after I ran some trials. We also don't get much snow for extra insulation. I have the Paradise EPS boxes and I now follow their recommendations. along with a couple of "improvements". 

One of successful beekeepers in Dawson City (one of the coldest beekeeping areas in the world) uses both top and bottom entrances. However the lower entrance is usually covered/blocked fairly early in the winter. They also get much more snow then my location. 

From an engineering perspective, heat through the top cover (no top entrance) is 15-25% higher for a hive with equal R-value. I usually recommend folks have at least double the insulation on top. If they do need to use a top entrance, I recommended that the bottom entrance be very small to reduce the heat loss via top entrance. 

Read the August 2017 ABJ Derek Mitchell article if you want a technical read on the subject. 

I also tilt my hives towards the back so the condensation flows away from my bottom entrance and down through my open screened bottom board. (all side and bottom are covered by snow/insulation so no direct air actually flows up). At temperatures below -30C the bottom entrance will freeze if tilted forward. Did that done that (following typical advice).  I shared this attached picture in a previous post. The goal is to push the heat pocket as low as possible (hence lower the condensation/dew point/contact area).

I will have more to say on this subject in mid March/April when I get my 1st chance to look inside my hives. My experiment this year was to have very high R on top Vs sides with and without a moisture quilt. So far things look good with a couple of small tweaks. My usual moisture quilt allows me to access top of hive without disturbing cluster to add candy/patty/liquid feed bag or check moisture wicking material. I regret not using it this winter as the old style was too high for this years trial setup. 

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