Sounds like a neat device...I have never heard of it...Probably designed for hearth cooking...set it close for direct heat and the box would act like an oven at the same time...move it back for less direct heat...
Slow roast birds are definately an excellent product..I usually need at least 2 1/2 some times 3 hours to roast a chicken to the proper doneness. All depending on fire control with all of its factors. Be sure to check out my "outdoor kitchen etc." In the member photo section under "Where we live"... The SS Rotisserie is kinda hard to see..It is 1 horse power...ME!
I am fairly new to the brining routine...It does a good job on poultry products and pork and some "seafood" items...There are numerous recipes for the brine.
Several here on DC....Most are a basic brine with variations on a theme depending on what one likes. I brined 4 big pork chops for about 2 hours using a basic brine plus a literal "handfull" of sausage seasoning...Then slow grilled...You could detect the sausage flavor but not so much as to think you were eating sausage rather than a p-chop.
I can recommed you try brining as it does make for a tender and moist product.