I am not sure what you are wanting to "clone' here.
I have had the pleasure of cooking on a Jambo and have stated that "If I was ever FORCED to go back to stick burning--it would be on a Jambo"
But, it is basically an offset stick burner with an incredible level of craftsmanship for fit and finish!
A work of art, to me.
Yes, Jamie controls temps (for the most part) with the exhaust.
You could do the same thing with a standard "variable" intake area and go from there. Just find an intake setting you like and play with the exhaust if that is what you are looking for.
The temps in the cook chamber are nothing unusual--hotter next to the firebox and cooler at the exhaust end.
Insulated fireboxes (not unique to Jambos) rock and really help with temp stability and fuel usage.
Good luck in whatever you are looking for.
"Flirtin' with Disaster" BBQ Team (RETIRED)
FBA and KCBS Cook and Judge.
Former owner of a WSM, a Smokey Joe, a Charbroil Commercial gasser (junk), the legendary "StudeDera" and Sherman.
Now cooking with a Fast Eddy PG500
Proud Pellet guy cooking on real wood.