Wayne, couldn't you have separate tweeter and woofer cabinets, with both the 4Pi and 7Pi crossovers installed?

The tweeter cabinets would have separate binding posts with cables connecting to the bas boxes. Then you could install both crossovers in each of the bass cabinets with separate binding posts for bass reflex 4Pi use and corner horn 7 Pi use on the opposite sides of the cabinets.

Wayne, is the "home plate" shaped top and bottom cabinet pieces and the vertical pieces in the corners needed for acoustic purposes? Couldn't I just promise to position them correctly (maybe using a template)? (Then the 7Pi cabinets would be simple rectangles.)