Just my 0.02 but I really think 200 degrees is too low of a temperature. I cook a pork shoulder and briskets to an internal temperature of 200F (measured by a meat probe thermometer). I tried 195F internal temperature and it did not reliably produce tender shoulders. I maintain a temperature of between 220F and 230F. At the point of about 1 hour per pound, I'll raise the temperature to 250F (and I keep the smoke up too). This yields a shoulder or brisket that is done in about 1.25 hours per pound and is falling apart tender.
Now here's why 200F is not good. The temperature rise of the meat is proportional to the difference in temperature between the smoker and the internal meat temperature. The temperature rises rapidly at first and then slows down as the gap in temperature decreases. There's a graph of this in the pork section, post: "Pork Butt Cooking time". This rise is mathematically described by a formula known as an exponential function. But think of it as a child's game. You walk half way to a wall. Now do it again, walk halfway to the wall. Repeat... Theoretically you will never reach the wall! An exponential funnction is that way (see the graph). You will theoretically NEVER reach an internal meat temperature of 200F with an ambient temperature of 200F. You will for all practical purposes reach it in many many hours but by that time you have made jerky and not barbecue.
God Q is a tradeoff between cooking time and temperature. Too long at too low a temperature and the Q will be dry and tough. Too high a temperature will result in done meat but not tender meat because the meat did not linger long enough to render the fat and allow the collagen to tenderize.
I used to think that 180F was the right temperature. I just hadn't thought it through. Sometimes I made good Q and often I did not. I did not understand why. Now I know that when I made good Q, it was probably that I did not actually maintain 180 at all but the old smoker drifted up to above 220 long enough to get a good cook despite my (mis-directed) efforts.