You know... I love the BTs. I haven't owned one, but a number of folks in my
training club think my Rosco is an Am Staff/BT cross because of his muzzle
shape (Roman nose) and his movement, so I may have some BT in my house after
all. I've also worked with BTs and Mini BTs in shelters.
I put the BTs in the same category as owning a pit, or other bully breed in
terms of DA and stubbornness/terrier traits. Which means expecting them to show
some level of DA and counting yourself lucky if your dog doesn't happen to show
that characteristic. Lots of training required and in the case of the DA, a
lifetime of management.
Of the BTs I've met, the common characteristics were: goofiness, play/ball
drive, and very food motivated. I personally think this makes them super-easy
to train. A mini that wasn’t DA would be awesome to run in agility.
In terms of planning what will be good match for T-Bone, I'd see what
he's like as an adult and pick a dog that will mesh well with that, maybe
adopting an adult he gets along with. I am only saying that because you've
mentioned T-Bone being on the more assertive side of the temperament spectrum,
and sometimes that doesn't mesh well with an equally assertive bully breed
type. That being said, Rosco is a cow 95% of the time and Luna is a bossy,
sassy Aussie and they get along really well as house mate.
JMO though and curious to see what others add.