For some reason it didn't occur to me to test both lights together using the "flash button" under the clutch lever. But my impression, supported by the pictures in the link, is that the main beam covers the same area as the low beam. In my car, the main beam gives you visibility further ahead on the road. In the pictures from my XT not so much. On a dark road in the woods I kept switching back and forth between main and low since I couldn't decide which was better.

I will do the mod though. It should have been done in the factory.