To paint over ANY surface, without sanding, use a product called 'ESP Easy Surface Prep', available at hardware and paint shops. Wipe on, wipe off and paint in 90 minutes. Works well over enamel paint , without having to sand. SAVES HOURS of work. It was recommended to me by a professional painter.
Your backsplash can be like a snazzy pair of Laboutin pumps that adds the sass and glam to the space....a great website for affordable metal backsplashes like this is www.glasstilestore.com (look under metal tiles!