I know that this is an age-old question as to whether there is any advantage to using SS line over rubber and and many people who have real world racing experience will tell you that there is no difference as far as brake feel. I do have some first hand longevity experience from a car that I once owned that was about 20 years old and one of the front brake lines had deteriorated to the point where it developed a small pinhole leak, but I noticed it before it became a danger to myself and others on the road. I'm of the opinion that failure of a brake system in a car is one of those things that have an extremely low probability but potentially extremely high consequences if it does.
My personal feeling is that unless you're racing the Baja 1000 or in a situation where abrasion or road debris could be a problem, there is no discernable advantage with SS lines.
My initial reasons for wanting to go with SS were 1.) I like the look; and 2.) The cost of the rubber ATE lines were going to be about $170, vs. $129 for SS from Turner Motorsport.
I did a little more poking around and found that I can get all 6 lines (ATE!) from Pelican for about $85, so I'll probably just end up going that route and save the $45. I'm not even sure that the lines need replacing (they likely don't) but after my experience with the leaky brake line years ago and the fact that my car is 15 years old, $85 is more than worth the peace of mind for me when it comes to a brake system.
As far as rubber lines being steel reinforced- I've cut open many brake lines and almost all of them are nylon/fabric reinforced. I know that there are some OEM lines that use steel reinforcement, but my experience tells me that they are in the minority. Additionally, after poking around a bit online, I notice that many SS lines are not DOT approved. DOT approved brake lines will meet whip (35 hours of flailing), ozone, salt spray, cold flex, and tensile (325 lb) tests. I suspect that the not-DOT SS lines do not meet these standards (especially the whip and cold flex tests, as teflon tends to be a little less forgiving than rubber). For the record, the Turner Motorsport SS lines are DOT approved (or so they claim).
Now that I've spent the last hour or so geeking out on hydraulic systems, it's time to go replace the belt tensioner shock on the M42...
