The red over green
lights positively identifies the vessel as a sailboat, no other vessel can display red over green(previous reply refers to red over white, which is a Pilot vessel). With
lights on deck you will be identified as a "power vessel" when sailing at night. This is a dangerous situation when a power vessel fails to give you the right of way based on his assumption that you are also a power vessel. Masthead
lights are a pain to replace though and add some weight and windage at the top of the mast. For cruising and ocean crossings, I'd go with the sailboat
lights, red over green.