This is the yacht on the mooring closest to mine. Amel Super Maramu, 53 foot ketch. We have had some brisk Westerlies during the week and often with the wind over the tide. Mate went past yesterday and noticed her hanging on by a thread! The rope risers looks like a mixture of silver and nylon and the plastic hose as the chafe protection. Looks like the usual sharp edge of the plastic cut through the silver strop! The nylon part of the riser probably rubbed on the anchor and the plastic tube there just slid up the rope.
Being the community minded guy you are and with self interest in mind, you did something about it.
A 53 foot ketch banging into a 30 foot sloop is not a good scenario for the 30 foot sloop.
Your point about plastic hose hardening in the sun and slicing through rope, I took onboard the first time you mentioned it.
Irrigation hose is the best anti-chafe solution for mooring lines. I have proved that with my mooring.
My yacht is just inshore of the Amel and safe if she came off in a Westerly. Upwind I have concrete and steel yachts! I worry more about them. The plastic hose is only a couple of months old! I like the flat fire hose [blue polyprop] for anti chafe as recommended by the US coastguard.
I've never had a problem when using chain coming onto the boat. It takes a while for the links to chafe through. 
We have built a couple of mooring bridles for customers recently which are encased in Dyneema Chafe Sleeving - easy on the boat and great abrasion resistance. Attachment to the fixed mooring line can even be via soft shackle to keep everything "soft".
They can and do come off the moorings, Im supplying two of my magic boxes to a boat owner in Adelaide. One of his two commercial boats broke off its mooring in a blow recently. He said damage bill after getting the boat off the rocks and fixed was $100K. He wants warning if either of them come adrift ever again. Similar story re a 60ft cruiser in Balmain, he was lucky since his boat got stuck in mud and nothing too drastic. Except he didnt know until two days later!
