I wouldn’t be too hard on yourself on the chuckroasts. If you want 140* finished chuck, I’d say a sous vide technique is the way to go, followed by an ice bath and then with a sear to finish. As you mentioned, the two were different, and the brisket chuck, had time to render and break down like a brisket, as you took it up to 200* I’m assuming. For the rib roast, you will be very pleased with a technique cooking to 140* give or take, and that would be using just wood chunks for the smoke.
I can’t comment on the Bella though, as I do not have it. I know there are a few on here that can comment, hopefully they’ll help out prior to tomorrow.