In reply to FreeloaderJoe:
Tag lines are perfectly useable, not as nice as abbing on two ropes of the same width, but they're fine.
The main problem when abbing with tag lines is normally the tag line getting tangled. I've not used the beal back up line, so can't really comment on how tangly it is, but having held one it seemed like it would be a lot less tingly than using normal 5mm cord.
