Used the smoker a few days ago for the first time. Without the "cold smoker" attachment I wouldn't be as pleased because it would need wood so often, but I was over all very pleased with the results! I had the top baffle about 75% closed the whole time. I see why people use a dimmer online with the cold smoker attachment, which is refered to as a "slow smoker" in the manual that came with it, potentially because it puts off too much heat to be "cold" unless maybe to 50F or below outside.
I used a motor speed control intended for a [wood] router. It uses a Triac/SCR, not PWM or variable capacitance, so it works great for resistive loads. I didn't put a meter on it but the knob was about 75%, just at the bottom of the "green" range on the knob. It was like $15 from harbor freight if you don't want to mess with putting a dimmer knob in line with it. I'm an EE so a knob would be a cinch, but I already had this speed control so I saved myself a trip to Lowe's and a few bucks.
http://m.harborfreight.com/router-speed-control-43060.html