Tuckaloe, there are many people here with tons more experience than me, but I'm learning as I go too and can share what has worked well for so far. We just had PBC ribs for dinner, in fact and they were excellent. This was my third go with ribs.
I cooked them in the barrel until the end of the bones were showing a little but I couldn't really move the bones as I've seen described here, and a toothpick pressed between the bones went in fairly easily. To be honest, I lost track of time, but this was at about 3-3.25 hours in the PBC I think. I then gave each rack a thin coat of BBQ sauce, wrapped them in foil and put them in the oven at 300deg for 90 minutes. At this point they were so tender you could easily pull the meat off the bones with a fork. No, I don't eat my ribs with a fork - just did that to test them! Oh, these were St. Louis style ribs, by the way.