Pardon me for resurrecting an old thread, but I'd like to get some more insight on this whole "to insulate or not" topic.
A while back, I was so bent on insulating my COS that I spent $70 on a box of ceramic insulation. I was also thinking it would come in handy for a brick and stone smoker setup I'm dreaming of building someday. The idea was to build the most ridiculously insulated smoker possible. That would result in super stable temperatures with much less fire management time, right? Well, I thought this was a great idea, until my buddy Franklin made a simple point in his book: If your smoker is too well insulated, it basically just becomes a glorified oven. Since you don't add wood often, there is very little smoke present and hence the meat doesn't get smoked so much as it gets baked. Very good point, IMO. So then the goal becomes to build a smoker with enough insulation to keep a stable temp, but not so much that you're not adding a new log often enough to keep the fire smoking nicely.
However, I am also thinking that if you have a super insulated smoker, you could still design it to keep the temps in the cooking chamber down while adding firewood regularly. Then, you could have a super stable temp AND a lot of smoke. If so, the question becomes "is it worth the effort of the extra insulation and more firewood used if you could just build a leaner smoker with more variable temps."