A tricolor light will draw less power than 3 seperate fixtures. If you're going to install an anchor light at the top of the mast anyway, it might make sense to install a tricolor/anchor light combination.
But, you still need deck mounted lights. You can't use an anchor light while underway (although I see it done frequently). A sailboat under power needs to show a "steaming light" and not an all-around white light.
As far as I know, the rules state that the steaming light must be located above the sidelights. You can't use a masthead tricolor with a steaming light.
I suppose you would use the tricolor offshore, for better visibility to shipping and to conserve power. Near shore, the deck mounted lights are more likely to be seen against the clutter of lights on the shore, and should be used when the engine is engaged.
Seems there are many more choices in USCG approved LED nav lights in the last year or two, and some are fairly reasonable in price. This should only get better.