I have to believe that insulating the firebox is a good thing - not a requirement - just a good thing.
Edgar is so stingy on fuel for his size that something good HAS to be coming from all that insulation... just my .02 cents worth ...
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)
smokechac, I am with Rick on whether it is needed or just an option. Insulating the firebox on an offset is definitely a plus in colder climates but it certainly is not needed. If you plan on a warming chamber on top the firebox then you cannot really insulate the firebox top and in my opinion this area is where most of your heat loss is so the rest is sort of a waste. In my opinion it will take a very long time to justify the extra cost of an insulated firebox over a non insulated one. The reason being is depending on the cooking chamber and the set up along with the pit masters knowledge of fuel management will play a large part in its efficiency..The only real advantage I can see is if you have folks that hang around the cooker they wont get burnt if they accidentally touch the firebox.