"I was told that a black wire was more to Code?"
What does more to code mean anyways, aren't your compliant or not? Guess he is saying it depends on the inspector :P
Why would the NEC allow other colors if you were not to use them? This is a perfect case for using a different color conductor, allowing easy idetification of what's going on with a curcuit.
I personally use black, red, blue for my branch circuits (120/208) and other colors for switch legs, but this is not required or recommended in the code anywhere that I have seen. Unless you have multiple voltages in a building, as Ryan_J pointed out.
