Easton Axis shafts have been around for a while in the traditional black carbon color. They are narrow diameter, like Carbon Express MFXs, less than 5/16 inches, which is the standard for most carbons. I do believe the smaller diameter increases penetration, but it's not really needed on deer size game. The smaller diameter shafts, because they lie closer to a bow's center when on the shelf, may be easier to tune, but I don't think that's a biggie either. Because of the smaller diameter, their walls are slightly thicker, which may increase toughness. Don't know.
A number of carbon manufacturers have been putting brownish wood grain patterns on their shafts and calling them traditional. A marketing ploy for sure. Easton is just the latest to do it with their Axis shafts. I don't shoot carbon much, but when I do, black works just fine for me.