Robt Mann wrote

.> Several aspects of this interesting discussion quietly imply
> drawbacks of queen-excluders.

Whilst there may seem to be some drawbacks, the drone brood above the
excluder is very rare.  For most beekeepers in Australia, the advantages of
excluders certainly outweigh any small disadvantages.  We could not keep
bees, at a profit, if we did not use excluders.  I admit, that for some in
other countries, it might be OK to run without excluders.

Trevor Weatherhead
AUSTRALIA