Has anyone used them?

Does the PVC tubing they use to protect the lines wear out quickly?

I don't think its pvc, urethane more likely.

Yeah I know, I've got some hydraulic high pressure hose, I used this on my old harness lines and it worked a treat, outlasted the velcro on the bit that attaches to the boom.

I was just wondering if anyone had used these, because it's easier to replace the tubing when the rope is new, rather than when it's old and has permanent kinks.

So I guess no-one's used these particular lines?

Yes it's called the reactor bar and I've been using the same one for years and ezzy do harness lines that have clear hard plastic covers so you can see if the rope is wearing inside
Also Nebs a cheapish set of adjustables might be OK short term to get the most suitable length right for you then go to fixed