Great looking pair of cabs - I'd really like to hear these to be able to compare with Tannoy drivers.
Interesting on the tweeter attenuation too.
They are great for all sorts of music listening, and I bet you find yourself doing just that - listening to the music...
Did you consider a tear drop baffle thingy in the throat? I put one in to a pair of BTH 18" dual backloaded horn cabs (ala GRF-R's) only bigger and it worked well.
There is talk about it on the Tannoy hilberink site I think it is.