Frank,
This is my 69th year of successful beekeeping, but I still have a strong back.
I am a retired scientist, and I kept bees as a scientific study rather than
for money in honey production.

Twenty years ago, I became violently FRUSTRATED by having 4 different size
hive bodies and 4 different size FRAMES in my apiary of 60 colonies, and I
asked myself WHY?  I was using deeps for brood chambers, and mediums (6 5/8")
supers, shallows
(5 11/16") supers, and comb section supers.

I converted EVERYTHING to just one size body, the medium (6 5/8") so that I
only have ONE SIZE FRAME and ONE SIZE FOUNDATION for everything (nothing to
do with a bad back).  I use 3 mediums (30 frames) for my brood chambers, and
those 30 frames equal 101% of the area of 2 deep bodies with 20 frames.
TOTALLY FORGETTING the weight difference of 90 pounds compared to 60 pounds,
using 3 bodies for brood chambers instead of 2 deep bodies has many
advantages particularly in REVERSING to help control swarming.

Many of my "students" have adopted my thoughts and use ALL mediums, and are
VERY HAPPY.

I would not use all shallows, as some companies now consider shallows to be
obsolete, and don't make them or foundation any more.

I hope I have helped.

George Imirie
Certified Master Beekeeper
Author of the monthly George's PINK PAGES about how to be a successful
beekeeper.  It can be found on the Internet under:
www.cybertours.com/~midnitebee/                         or
www.beekeeper.org/george_imirie/index.html