RPING----it is my opinion that you do not need a water pan in your MAK. Or any pellet grill for that matter. When I first began cooking on pellet grills in 1991, I had switched over from using watersmokers, and put a water pan in my pellet grill. It didn't add any moisture to the cooker. I measured the water before and after and there was little to no evaporation.
Yes, I believe that the water pan may have caused your brisket cooking time to be longer than it needed to be. Using the 2nd shelf was good because heat rises.
I am not an advocate of foil, because it steams the meat and softens the bark on the brisket. But, if it works for you, then that's what matters. Your smoke ring is dead-on.
The difference between Prime and Choice is the amount of interior fat in the meat. Either grade is fine. I usually go choice only because it is less expensive on a per pound basis. But again, whatever works for you.
I agree with many of the replies on this thread that suggest raising the temperature. 250F-275F is a good range, it will help the brisket cook more quickly and still help to break down the meat fibers. I smoke my big cuts longer than you did. I would smoke a brisket for up to 6 hours, then raise the heat to bring it up to a finishing temperature of 200-205F.
