You make a very good point there. But I'd stick to the normal 4 lightsaber colors. None of that goldish crap. It wouldn't be a bad idea to give Dooku a green saber. In fact, I really like the idea. Anakin had a blue saber in ROTS so it would make some sense if Dooku had one.
Especially if Dooku had a couple of scenes in TPM in the Council or wherever.
The one thing I dont like is that we need to focus on the main plot, not Dooku.