Over the last couple weeks I have seen a lot of brisket post and a lot of those people were pulling at 180-190. folks, let that thing go to 195-197 if not a little more. I can tell you a 180 sliced brisket and 197-200 are not the same. A perfect brisket slice should be able to fold almost in half across your finger if you slice it the width of a pencil. You should also be able to pull a brisket slice side to side and it should expand to see through parts but not break. Just try it once.
Also, trim the fat off. Fat takes time to cook and break down. No need to cook 3lbs of fat that is getting cut off and thrown out anyway. Where the biggest chunks of fat are aren't going to help keep your brisket moist.
If you get a flat that is under 7 lbs I recommend wrapping in foil when in the plateau and put some liquid in it like 1/2 can beef broth. Most flats I've seen that size aren't thick enough to really maintain and moisture and tail off to the end. Always try for full packers if you can as you can use the point for burnt ends but your slices, especially those above the point, will be much better then the flat.