Apis,
I did use bottom supering and it worked well as long as there was a strong flow on. I did have one colony that no matter what, they could not be encouraged to draw out comb in the bottom box. I had to always super additions to get them to fill them. Told my wife i was going to photocopy Warre's book and pin it to the hive so they would wise up.
Abbe Warre's idea was that foulbrood resulted from using broodcomb over and over and by rotating it out the small operator, (his target reader), would avoid the disease. He also didn't have to deal with mites.
I'm convinced now that they work just fine for a few hives but inspections and manipulations are tedious and frames solve that issue. Without frames the boxes are roughly equivalent to 8-frame mediums in volume. To make up for the space lost to side bars and side beespace i will make my boxes 1-1/8" deeper.
Another advantage to frames is extraction. Top bar combs can be extracted but a specially built wire cage is required to minimize comb damage.
I do like the square shape of the hive boxes. They are more ergonomic for lifting and (I think) a better shape for wintering.