Sorry..I really didn't mean to reopen this can of worms.
Yes... you still get some expansion with steel shoes but
it is limited and not to the extent a barefooted horse
experiences. And some materials do allow for more expansion
than others.
On the growth issue..yes the toe grows on a shod horse
but often times you limit the heel growth due to not being
able to completely expand when meeting the ground and
decreased hoof circulation due to no frog stimulation.
Over the years you begin to see some contraction. With a
good farrier this may be very slight over many years but
nevertheless it is there. I have yet to talk to a
knowledgeable farrier who will disagree with this.
More importantly with steel (and most shoes) you get no
frog pressure which encourages circulation.Which by the way
is the main function of the frog. Another hoof mechansim
that is compromised by shoes. This was what drew my
attention to the ground control shoes when they were
discussed on RC a few weeks ago.