Jeff - you are the 3rd person I've heard from that reached the same conclusion. Uncoated 316 stainless appears to be the most cost effective solution.
Comment - I am having stainless tubes welded in the stanchion holes the wire passes through to minimize chaffe and get rid of the plastic inserts. That should help increase the longevity of any life line.
What did it cost to weld tubes into the stanchion holes (per stanchion or total)? Who does that kind of work? A rigging shop?