I have noticed two schools of thought: run ventilation through the hive so moisture escapes and minimize open interior space and put insulation in the attic (above top board or top bars and under roof). I subscribed to the ventilation approach with upper entrance until I checked my hives mid winter and found a moisture mess. Then changed my approach and insulated the attic and it solved my moisture problems (this same theory would work on TBH's). The way Finsky explained it to me...and it makes sense...is that hot humid air from the cluster will condense moisture on a cold wall (like single pane exterior windows in winter). With my upper entrance, the whole inner cover was cold and condensing moisture on the bottom of my cover and the underside of my inner cover and creating mold. When I placed insulation up there, the moisture began to condense on the sides of the hive (away from the cluster) and dripped through my screened bottoms onto the tray...no more moisture or mold problems. Finsky doesn't use SBB's, but has drip holes in the corners of his BB's...which I will try on my solid bottoms when I can swap them out.
Not saying upper entrance ventilation won't work, but it didn't work for me, the way I was doing it...in our cold, damp, winters. I'm sure one major variable would be where your upper entrance it (front of hive body, below inner cover versus above, etc...I may have been making a mistake by having it above the inner cover rather than below...