In fact, I think the slight difference in hue looks really good, and now I'm curious to try it with blue buttons and a green screen.

Hmm, not so good. The problem is that the knob sits atop a section of the colored faceplate. So you have green backlighting shining into blue plastic. This dims the light of the knob too much. So your button plastic really should match your face color, at least with this pass of the knobs.

Now, if Brian came up with a way to distribute the light more evenly, and we did gray translucent buttons, I think that would work. We would have either a slightly-colored knob when the lights were on, or we could mask off that under-the-button section of the faceplate with black tape and depend upon the knob collar to collect the button light.