If you were going to recolor Dooku's blade, why not use the yellow one from MagnoliaFan's "The Clone War?" I thought it looked great, and it also made Dooku more ambiguous. The film as a whole seems to work better if Dooku is less Sith and more of a rogue Jedi.
As for blade colors, there ought to be a wide spectrum - orange and yellow definitely, in addition to green, blue, red, purple.