Remember Jim Gibbinson's book on carp where he used bright yellow line, as were plenty of local anglers? (In France, I think?)
With great success.
My Daiwa Sensor is clear (they do it in black???), but the number of successful anglers I've seen using green or brown line leads me to believe it probably doesn't matter what colour it is with the rigs we use these days.

---------- Post added at 20:36 ---------- Previous post was at 20:29 ----------
And just found this:
line colour