Ryan, if you're going to err (not saying you did....), err on the side of falling apart vs. chewy. I've many times cooked a brisket 200+ degrees internal in the flat that would not slice well. (Definitely wouldn't pass the "slice-over-the-finger....then pull apart" test.) And, in those not-so-rare instances, I've made some of the most amazingly tender brisket sandwiches you could imagine. My buddies at work LOVE when I "overcook" a brisket!