BNS, knowing you have more experience with boas here, I'll defer to you.
I've found that I prefer breeders who know their animals and can tell me if one animal in particular is less defensive than another, a better eater, etc. This goes for all reptiles, not just boas.
As you say, the above may matter little long-term in terms of temperament with BC's, but it tends to make me more confident with the breeder; that they pay attention and know their animals.
Either way, thank you for the post. I always appreciate your insight.