Quote - I tried using the bitmap for root, tip and specular colour and that minimises the shine, but it may not be shiny enough for some people.

 

Easy..  use the map as is for root and tip, and use the very slightly lighter version of the map for the specular.  I'm sure BB can tell you an easy node to run it through to do that without having to actually make another map.  (not a primary poser use, don't know node majic off the top of my head)