I had Northwest Labs in Seattle break test a rope I had hanging in a tree for 18 years. One side of the rope was picked from UV where the sun hit it. Was a half inch line, but it had absorbed moisture and swelled up to about 5/8's size in places, and in the shady parts of the tree it was growing moss. Perfect for a test, I though.
The line was originally rated for 6,000 lb and broke at 3600. Not bad considering hanging in the elements all those years. I never would have trusted it, but after the test I thought, if it come down to it in a pinch, I would.
Break tests are way cool.
Its obviously not mine. Its a real privilege though to have it available. I have wondered countless times 'what will this hold like this', or 'how strong is this', 'I bet this will hold'... Now I just run over to the break machine and figure it out. Its not a huge machine but it will figure anything I need it to.
. Ya know, try to pull it apart as if it were a steel ring. If you tie it off in a favorable, load-spreading manner (like with hardware that would be square with the flat inside surfaces of the roll) I bet it would hold 1000 lbs. 
