Far as I know ALL drip rails are 2 pieces, the part that bolts to the cab (steel) and the face part (SS). Probably the painted ones you saw are just standard fare, were SS like the rest originally, but somebody painted them to suit their tastes at some point.
How it looks depends on the truck. for a stock looking truck, 's like it SS. for a more customized or monochrome truck, the painted would look even better. depends on the look you're going for really.