pros and cons:
pro:
- extra backup for the climber if the main climbing rope anchor point (llmb) breaks, etc.
- usd widely in industry (window washing, tower access, etc)
Cons:
- anothe rope and gear set to manage in the tree
- the second rope better be a DYNAMIC rope or a static rope with a energy asorbing lanyard to climber connection (to absorb fall energy if main (primary) rope fails.
- extra gear to lug around.
my 2 cents