Alright, great thread, but I have to weigh in also. Yes, I am fairly new to sailing, but I am not new to using webbing, ropes and carabiners in lifesaving conditions. I also bought a pair of 40' jacklines on ebay. Very well stitched with good quality hardware and top-quality webbing. People, these materials are so strong that they will never feel your weight if/when you fall and are restrained by them. The 1" webbing is rated for well over 1000 lbs breaking strength. The same holds for well-tied knots in quality rope. When you go up the mast using your good condition halyard (tied with a bowline), it is so much stronger than the load that you are applying that the safety factor is probaly more than 10:1.
Check the knots and stitching of any sewn loops in any safety gear, no matter the brand name or the amount of $ spent. That is just prudent.
Keep up the great threads. I am learning so much from you all.