"And the coating separated from the core just below the welded loop. But I used this line over many many trips casting many many times. I would still recommend it."
David, cut the line just above the bad spot and nail knot your leader to it. Then coat the knot and the end of the fly line with Clear Cure Goo or Knot Sense; that will seal the fly line and facilitate the knot slipping through your guide(s). I never liked loops, and that is how I attach my backing and leader to the line.
Bruce Mc, the Rio lines have a stellar reputation on the Gulf Coast. Buy Rio with confidence. I use mostly Orvis lines, and I love them, but that is largely because the local Orvis shop is staffed by great folks, several of whom are good friends, and I prefer to buy from businesses like that.