Even the 1/3 WL spacing center-to-center is a tall order given the mouth sizes of most midbass/midrange horns with a single driver (assuming they're being tightly arrayed). With baffle-mounted cones in a vertical array, I'd need a stack of differing diameters to cover the ranges up to the typical 1" horn/driver combo. This challenges one of my goals for each design: a 3-way active system (triamp with active x-over/processing). As my design ideas are aimed toward live sound reinforcement, I will likely see how often and to what extent I can "cheat" the C-to-C coupling guidelines, with as little compromise to sound quality as possible. In many live applications, the listeners are farther away from the audio source than with a home system, meaning more room to squirm for the live audio designer!