I've had several sets of these on different bikes, the polymer coating and the housing are very good in my opinion. Unfortunately, the 800mm long cable housing for the front brake is too short for slacker gravel frames with disc brakes and wider bars and longer headtubes. And this is on a 56cm frame.
These polymer coated brake cables are very slick. The installation was very easy, and am using them with the non 9000 or 6800 series brakes, (7900). I did take care though to scrape off the cable coating where it gets clamped in by the fixing bolt, I'm a bit paranoid about the cable slipping through the clamp. Great cable.
I bought this cable set for a bike equipped with Ultegra 6500 (Shimano does not approve the use of these cables without Dura-Ace 9000 brakes). The polymer coating on this set can be scratched off with sandpaper, so that is what I did when securing the cables in the brakes. Great set of cables, probably the best you can buy.