I don't have that problem with BD and I've used it since it first came out. It tends to be soft when new, so I let it sit in the corner of my garage for a couple months, or better yet, but a big spool in the fall and let it sit all winter to dry out. It lasts as well as any other line then.The worse part about Black Diamond is that it breaks off at the head often, and then you have to re-spool the head. This is particularly true when edging.
I agree with you about the high torque heads not being necessary. However, to me, the torque head sounds like it is spinning faster and recovering faster in the videos and I listened several times. Maybe it sounded different in person.