BC, I agree with you about continuing to color your hair. Letting my hair go gray would completely wash me out even with a change in makeup. I have been contemplating just let my hair go, but I love the way I look when my gray roots are colored.
Now I have a friend who went gray and it looks amazing on her and against her skin. I am not her!
Also, your hair colorist should be able to come up with a formula that works for you. My colorist friend devises individual formulas for her clients that many times takes a while to create for their specific desires. Hair coloring is a science.