"The reflex driver is XO at 175 Hz to the mid-horn. Again the integration with the whole seems pretty good, but not as good as with the mid and top horns."

I don't know if you can do it on your x-over or not, but try delaying the reflex-driver to match the depth of the mid/hi horns and see what happens. If not you may have to play around with x-over freq. between the reflex and the mid-horn.
HTH
Bill W.