I note that this is in Q-talk and not Comp. For backyard cooking I think you can choose just about any brisket and have a reasonable chance at getting a good brisket out of your efforts. To that end, I buy Choice if its there, but, it doesn't worry me to buy Select as Bludawg pointed out, the grading is not too important. If the cryovac is loose, I will do a flop test and a close visual check for a nice thick flat. If it is tight, I poke at it. In the end, it's a guess.
I will say, that the store makes a difference. Over the past two years, I feel that Cash and Carry has provided me with the better packers once the cooking is done
Whip It Off, Chambers!
"perhaps...but then again...maybe not..."