Don't forget the rest time after 180- it's important in that some of the juices will be re-absorbed by the meat during the rest. Leave it wrapped, and wrap in a towel on the counter for a 15-30 min. or so.
Good luck with your brisket smoke. Remember not to go by the watch as anything can happen when it's cooking low-n-slow. As long as your smoker temps are good, and your thermometer is calibrated correctly your brisket will be done when the temp says it's done and it will sure be worth the wait!