Splurged on a Kamodo Joe last summer, and the are the real deal for long and slow.
It took me about 4 dry runs, but I finally got it down last night.
First run was -pile lump charcoal, ignite. I couldn't control temps below 450 degrees or so, opened the vents and it shot up to 800+ degrees- it turns into a blast furnace when the vents are opened. Going to have to try searing steaks sometime soon.
Second run- piled charcoal, lit, kept vents partially open. I couldn't keep the temperature low, it ran up to about 350, then stopped.
3rd run- set up 'ring of fire' briquet charcoal arrangement, lit one end of ring. Temperatures climbed to 280 degrees, before it got snuffed by me trying to valve it back.
4th run- took bottom vent apart. cut a gasket from a roll of automotive gasket I had laying around. Put gasket between bottom air vent and control slider. Ran 'ring of fire' arrangement again- kept it within 5 degrees of 225 for 4 hours last night before I shut it off and went to bed.
I have ribs thawing out at home now, making them low and slow tomorrow as my next experiment.