I haven't yet, but I'm still tempted to, try an alignment such as this Glasstone/Boom/Xsonics thing with my 12" Deltalites, mainly due to their rising response in their upper range.
Thinking if one could throw 2 woofers worth of bass through maybe middle mids, then physically filter off 1 drivers worth of uppermids/low treble, the result would be a smoother cab than if both drivers were facing forward in a more traditional cab.
Problem is, though they don't give a "warm" sound by default, that rising response has been working in my favor in real world situations.
See...things like bodies (hopefully we have a lot of those out front of the speakers) as well as things like drapes, tablecloths, etc., tend to "soak up" or damp a good deal of uppermids/treble while letting a lot of the lower stuff through. So, even though yourspeaker might sound a bit hot up there up close, when you get out to where your audience is, it ends up "just right".
If you put a "flat" speaker in the same situation, by the time the people and the room got done doing their thing to the sound, it wouldn't be flat anymore, rather leaning toward less clarity and definition, more biased toward the lower half of the bandwidth.
Some may call this muddy, others may call it warm, and they'd both be right. It's a matter of opinion.
Of course, in a stage monitoring situation, that wouldn't apply so much and a "fat but still articulate" cab could be made with sttong output "where it counts" could be made in a fairly compact size.
Of course, mine would be made with an ear toward driving smallish venues on its own primarily, with having "righteous tone" 6ft. in front of it as a secondary goal, and thus would be a 3.5-4cu.ft. "proper size for a 212" anyway and not such a compact affair.
I could also see such an alignment as a useful way of beefing up something like a DeltaPro or EVM 12L in order to keep their superior topend while beefing up their "meaty" range for bass.
The old Acoustic 408 cab Is a good, albeit large, example of this with 215s facing forward with 2 more facing up/down to accentuate their lows/low mids.
Could also see it leading to mud with a driver who's emphasis was already on the lower side of things.....
Musings....
Back to your previously scheduled commercial....