Every brand of braid I've fished with over the years fades to some degree over time. As a habit, I take a sharpie and color alternating sections of line (spaced out every few inches) up the line about 5 feet to help camouflage the fading and the line. That way you can retie a few times before having to break out the sharpie again. Not sure if this actually helps, but I have confidence doing it.
Both Spiderwire Ultracast and Kanzen are super high quality braids. I like the fact that Kanzen comes in 80lb test where Ultracast maxes out at 65lb I believe. I haven't had an opportunity to fish Kanzen in anything other than 40 lb test so far, but will be using them all shortly. As I get some more water time with the other sizes I'll check back in with my thoughts.