Cool would be if it functioned well as a headlight.
Do we know how well it functions as an actual headlight?
While we're on the subject of "cool or not cool" in my opinion cool would be you rocking the headlight and not giving a damn what anybody else thinks about it. Cool is when you do what you want and you don't care what anybody else thinks. I have done a lot of things to my bike just because I
thought they looked cool. If you
think they look cool you should go with it.
The Bonneville is a modern retro, so I don't see a conflict with running that light as log as it was decent quality and provided better light than your current set-up.