Bill,
Jeff, dyeing never improves on nature. It merely provides what nature doesn't or at least not in abundance.
I'd go one step further. Dying provides a color that we humans see as a red or green or brown, etc. The trout may perceive that dyed material in a totally different color than the natural. That is why I don't generally use dyed materials.
Here's an experiment that I did a long time ago after reading a good bit of material on the subject. Get three different pure light sources (i.e. a single light source in say a windowless closet): incandescent, fluorescent and UV.
Get two samples of the same material, one natural color the other dyed. In my case I used natural wood duck flank feathers and dyed Mallard flank feathers. My samples to my visual eye were pretty darn close under incandescent light. Once I looked at them in florescent and UV light they looked totally different. Under the UV light the dyed material actually fluoresced/glowed! I then took them out and looked at them under natural sun light. They did not look to be the same color.
Considering all of this, I still say presentation trumps color matching but that's just me. In any case, I still favor natural colors rather than dyed.
Grant