I have tried a few of these this year and so far am pleased with the results.
 The brood extends right to the bottom bars.

The thought struck me the other day when I was looking at a colony without
using smoke and I could see between the frames and through the mesh to the
ground beneath that the bees weren't flying up at me as I expected.  I
wondered whether the fact that they were continuously exposed to light from
below during daylight hours meant they didn't bother to investigate when also
exposed to light from above when I removed their ceiling.

Chris