I finished floors and 'slatted racks' for my hives: 11 new floors with entrances from underneath and 8 slatted racks (after a trial with three this year). I'm grateful to JBM for the under hive entrance floor design that I found here. This design is easier than another UHE floor (kewl floor?) on the web, and I prefer that JBM's structure has a wooden rather than a Correx landing platform.
All I can say after one season of three hives with slatted racks is that it hasn't done these colonies any harm. I feel that the empty space near the entrance is somehow akin to the natural nest and I like the idea that the bottom of the brood frames (with stores too) is some distance from the entrance and separated by the slats. You can read about slatted racks
here and although they're popular in the US, and a very old idea too, I wouldn't know if the claims of these benefits can be substantiated. They're only available in the UK for Langstroth. The bought ones, like the plans available on the web, are stupidly over-engineered. The hardest thing for me was measuring for the positioning of the slats (directly below the frames) and that's not difficult at all.
However, the main thing I did during all this construction was listen to Mark Winston's book,
Bee Time: Lessons from the hive. It's a great read, especially the chapters 'Being social' and 'Conversing', which tell a much bigger story than the specific research by Seeley and his predecessors on the collective decision-making by scouts choosing a nest site for a swarm.