After kicking around my 2x10 horn design for awhile, I've given up on trying to get it to (theoretically) reach 1600Hz to mate with a coaxial 1" comp. Although I like the driver placement, I can't get away from the notion that I'm creating double front chambers prior to the 2 passages combining. Perhaps a better plan is to mate it with a larger format comp & cross in the region of 1kHz to 1.2kHz, then mount horn/driver on top.
I'm still hesitant to put any money into this project....