Lloyd Spear commented:
<snip>...
>All of my brood space is a 1 = story hive, with a deep on top and a 6 5/8
>(Illinois, or Western) super underneath.  The advantages of this compared to
>two deeps are considerable and have to do with reduced lifting and overall
>effort.
 
(many thanks for your followup comments, Lloyd)  The system he describes
does have a number of advantages.  Incidentally, this is also how the giant
Powers Apiaries operation is managed.  Having the deep on top allows one to
make up nuclei using standard brood frames; or if you need to pull some
brood out as swarm control, it can be compiled in a regular deep brood box
thereby creating or strengthening other colonies.  You can also pry and tip
up the deep chamber to look for swarm cells, etc.  All this would not be so
easy if the deep were down on the bottom.  Another advantage (Walter Kelley
mentioned this) is that having a shallow/medium super between the floor and
the deep brood box keeps the deep brood combs in better shape, since the
bees aren't so apt to chew away the bottom edges.
 
One dis-advantage is that you are messing with two sizes of brood frames.
This is not much of a concern, though, and in the normal routine of things,
you don't ever have to mess with the shallower combs down in the bottom
box.
 
This arrangement, still, provides considerably more space than a
single-story hive.  More like 1-1/2 or 1-3/4, at least during the height of
brood production.  There is still lots of excess comb-area beyond what even
an exceptional queen would require for laying, even if only 9 frames are
used.
 
I should add that with the wider spacing, the faces of the brood combs are
not drawn out more, except a little at the top, if there is nectar at the
upper corners.  They will do this with ten combs some seasons.  As far a
wintering goes, Chas. Dadant swore up and down that he got BETTER wintering
with 1 1/2" on-center comb spacing than with the 1-3/8".  That was one of
several reasons why the Dadant/Modified Dadant hive was designed with the
wider spacing in the brood nest.
 
I'd also contend that the slightly-wider brood spacing can contribute
towards more successful wintering.  Reason being, there are more bees in
contact within the actual cluster, instead of their being more isolated in
thin layers between the combs. Temperature regulation would therefore be
more efficient, not less.  I have not seen winter-kill or partial-divided
clusters due to this isolation since going to 9 combs.  (No hard data to
offer, but bees apparently do very will with this setup.)
 
Granted, uneven or haphazard spacing of 9 brood combs can produce a real
mess, and can make hive manipulations a great deal worse, not easier.
(again, had I new (or at least newer!) equipment, I'd probably use all 10
brood-frames throughout...