Thanks for the detailed response, SQUIB.
As far as losing too much heat, that could be a real concern, although being in the Dallas area we don't worry about cold as much as some places. I think I would have a pretty short pipe, and a square one like you suggested.
When I say maintaining 225 to 250 is difficult, I speak from experience, mainly on my COS New Braunfels cooker. Actually, 250 is a pretty good fire, but anything below requires checking the fire very frequently (sometimes every 15 minutes). Basically it would just be easier to have a bigger fire roaring with bigger logs, a bigger critical mass of coal bed, and simply add a good log once every 30 to 60 minutes. Maybe that's unrealistic. I don't care that much about efficiency because I have more oak than I'll probably ever need. And I like big fires.
On airflow/smoke distribution, I realize a lot of my imagination about what happens inside a smoker might be incorrect, but I picture it like water, which I can visualize based on experience. With baffles, water would have a lot of eddies or "stagnant zones" where the water doesn't recirculate nearly as quickly as in a straight, smooth pipe. But perhaps the flow of smoke is way more turbulent than I imagine and it doesn't make any difference, as long as it gets in the chamber. What would be really nice is a glass smoker to see what the smoke really does. Totally ridiculous, I know.
I've got nothing but time for a while before I start the build, so if y'all get sick of my musings, feel free to tell me to shut it.
