Hephaestus I like you're idea!
Oh yeah I built one similar.
I'll share some of my smoking experience.
Been out of the country for the last couple of weeks but I can see you do need some positive response.
Yesterday I smoked 19 turkeys all at once on my center fired. Turned out to be over the time limit and everyone had to wait 2 1/2 hours past lunch time.
My center fired is about 20 to 25 degrees hotter in the center! This allows smoking of different size birds, or meats, and still have them come out at approximately the same time.
I put the larger birds in the middle with the smaller on either side. We're talking from 11 to 21 pounds. I found this to be an amazing feature. Can't use it all the time but it does come in handy.
One important element is to keep an air space between all the turkeys. Then my smoker will cook 1 or up to 16 in approximately the same amount of time. I found my smoker's limit is 16 turkeys, more and the birds are stuffed into the smoker making one solid rack of meat. Really extends the cooking time. I'm sure most of you smoking gurus already new this, but I'm still learning.
Another thing is the grease drain on a center fired. I did list it down hill to facilitate the flow, and this does effect the temperature on the ends, but while cooking the whole smoker can be raised or lowered to get the heat and smoke flowing relatively evenly.
I put 2 9" diameter dampers between the firebox and cook chamber. I used sheet metal on stand offs for heat shields and they work just as well as brick! lighter and permanent.
Another feature of my smoker is I have to remove the grates and clean the burnt build up on the reverse flow plate. Especially in the center. This is more of a chore than a feature. ha ha
Still, I believe that because of the heat being under the smoke chamber this design is a bit more efficient.
With the Minion Method, Dragon's Breath will run about 6 hours on one 40 pound bag of mesquite lump charcoal plus the fruit wood limbs I put in from time to time for the smoke.
If I can help let me know and keep on smoking.