Good point on nylon fraying....I constantly look for wear and tear on such things. So far nylon ropes and strap combo has not been a problem. I like the caribiner idea except when the end of the line slips out of your hand and dings the paint job on the car. All in all, such clips are a good idea and work well with knots to aid in tightening it all down.
Kayak Deck Gear Bags
Paddler's Truck Rack