My normal routine for chicken was a super-smothered with apple wood smoke on an old open grill, raised up high from the fire below for lower temps (barring the occasional fires I would beat back with a camp shovel--you have to see it to believe it) for somewhere around 3 hours (depending on how much beer is in the fridge and how hungry we are). More on this whole setup in my intro post--I'll try to dig up some photos to add there. This was normally done with legs and thighs. I have been doing this method for a few years now and the meat is moist and tasty, and the skin is amazing (to a fault...fat content and all).
Anyway, I did a butterflied chicken on my offset smoker last weekend (my new WSM just arrived day before yesterday and still awaits the proverbial first smoke). I was cooking it along with some KS cut ribs, 3-2-1 method with temps between 225-250*, so when I got to the three hour mark the chicken halfs came off and I put them skin side down on a grate in the firebox of the offset for around 90 seconds, or so. The results were fabulous!!!! The skin was crisp and delicious. Dry rub only, no brine.
I'm thinking maybe the brine combined with low and slow = rubbery?
Just another data point since I am very new to this low and slow stuff and learning from you all!