Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
Dyed lines make an enormous difference over spooky fish.
I don't believe the color of the fly line makes one iota of difference.
But I can say that on the majority of quality wild trout water in the East, fishing a leader in the 12-15 foot class is not practical most of the time.