Well since this thread looks to have finished, I'll use it to continue the tangent topic...
I received my pair of JBL 2123H's last night. Whoa are those big mommas. I mean the magnets not the cones. They are seriously heavy woofers, almost as heavy as say my 12" TC2+ subwoofers, and this for a midrange woofer! I guess that is what you get when you go hi-eff.
They are seriously well built drivers. The paper cone seems very stiff for a paper cone, not like a lot of hi-fi paper drivers.
My intentions are to start with using my Arvo Part woofers (u-baffle with 2 12" TC2+ per side) and these 10" midrange together with DDS Eng 1-90 horns and a compression driver I have not yet decided on. The MT baffle will be removeable/modular to allow switching between the Seas W22/waveguide loaded R28a tweeter. The DEQX allows for a few projects to be stored so the alternating should be easy enough. Ultimately though the hi-eff setup will likely be broken out into its own system and mated with a hi-eff pro 15" woofer below. I think the DEQX should assist me in the crossover design when things get cemented.