Hi Guys,
It's Jeff, the Marinebeam prorietor (and 3x Beneteau owner). The answer is that the tubes are indeed brighter than the originals. This due to the LEDs employed, and the fact that they are directional rather than isotropic, so all the light goes directly out the fixture with minimal losses.
Of course, they will also outlast the original tubes and ballasts, and draw a pittance of the original tube and ballast's power requirements. While the technology is still relatively expensive compare to a fluorescent tube, they cost less than most replacement ballasts.