Welcome.
big MR fan here and the beartooth is a hell of a bag. I like mine a lot but I will say, I rarely fill it up for anything less than 3-4 days. I own a pintler as well and use that for shorter trips. If I only had one MR pack it would be the Metcalf or maybe a terraplane. You can strap the beartooth down pretty well when it is not full but it is definitely a large pack.
I like and use their backpack lid for side excursions. I think they come with the beartooth now. The one with shoulder straps. another decent accessory is a bag of some sort to contain items on the meat shelf. I use an MR dry pack. Loose items can shift or fall out so I like to have something to give them containment.