I can't give a definitive answer either.. but here are a couple of thoughts.. There are a number of good/popular places around here that do smoke cooking. Some are huge above ground stone pits with thick metal grates on top. The temps are controlled similar to using a Weber kettle.. fire on one side and holding temps on the other. Others are commercial offsets. In both types they throw in seasoned oak logs with bark on. The smoke flavor is excellent.. and not bitter.
I've asked the same thing about using barked woods in the CS and received the 50/50 answers that Wheelz mentioned. My first cooks I used Alder with bark.. the next few cooks I removed it. Not sure I could detect a difference.. but, maybe my palate is not as sensitive as others??? I have not used barked woods in my smoker since. I guess my reasoning is that the ratio of wood to bark, beings we are only using 1-4 oz of wood, might be a bit high.
In the first examples they were using split logs. Had they been using branches where the bark to wood ratio was higher.. the product might not turn out as well.. Like I said.. I don't know the answer.. but, you have something more to think about.