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