I use a stoker on my offset stick burner(custom made) and yes they do work, took reserve grand last year using offset stick burner with stoker and multiple places in the 2 contests that i cooked. I often cook at 350 and use the stoker to maintain that temp. That being said you still have to have good fire management and building (small clean burning fire). I have my air piped in the fire box as to keep the fan away from the hot outside of the firebox. here are some pics of how i have mine piped in on my old firebox.
just got a new firebox put on that is double insulated, custom work done by TuscaloosaQ or TQ that has the same pipe put into the firebox you can see where the outlet to hook up the fan is coming out by the back of the firebox.
is it necessary probably not, but will it keep temps where i want it and be more fuel efficient, i think so and i have drastically cut my fuel consumption since i started using the stoker in 2010.