one thing I think should be considered is the fact that a paintless finish is light, elegant and most importantly is not easily aesthetically damaged; meaning that small scratches are generally less visible than normal paint, there is no risk of paint chipping off and it is also much easier to restore with some clear coat.
by default, I would go for paintless glossy finish and I would rely on other components to create some contrast, for instance silver hubs and spokes (I think UAE uses this color scheme in some races), silver decals on the downtube, etc.
in case of custom color, maybe something like this...with the front of the bike painted with some color that creates a significant contrast with respect to the rear end, that will be again paintless glossy. but I would make the color transition much closer to the front of the bike, basically painting only the fork, head tube and 1/3 of top tube and down tube.
