Does colored vinyl sound worse than black vinyl?

No, not when it is pressed properly.

The old reputation came from older records and older processes. Our pressing engineers hold that a solid color, pressed with the right polymer mix on modern machines, is not meaningfully different from black. That position is theirs, made on their own presses, and they will say so directly.

Effect vinyl is a different matter. Smoke and marbled vary more from copy to copy than a solid color does, because the mix is never identical twice. That is one more reason your test pressing is where you make the call. Do I get test pressings?