Mick, I'm in Northern IN and used Queen excluders on mite resistant Carnolian
bees, three from Kelly and one from N. California new packages this year.
 One hive nothing,
one hive one full deep box nothing above the excluder,  one hive three deep
supers all without queen excluders after the main honey flow and still going,
with two shallow and one Il. depth boxes of nine frame honey ( a really good
hive) and I used excluders for the shallows.  Those were the kelly hives.
 One N. California hive put in one month later from package bees (3lbs. as
were all above) with one shallow and one IL depth super above queen excluder
and after removal, one deep super without queen excluder and still going.
 
So, I think it depends on the strength of the colony.  My weak colonies did
not go above the excluders but my strong colonies did and made a really good
crop and kept their queens out of the honey supers while using the excluders.
 The only reason I am getting the deep boxes of honey is because I thought
the flow was pretty much over and I don't particullarily like goldenrod honey
so I hoped any residual honey would be made for the winter.  Well our
goldenrod really hasn't taken off yet and I put Apistan in the hive so now
I'm going to have three deep boxes of honey plus whatever fall flowers the
bees use.
 
The deep supers were filled in two weeks, really amazed me.
 
Don't know if this helps but good luck