Mine are filled, i will take a picture tonight and post it for you. I like it, it is a clean look. BUT... I dont drive mine except for fun, never in the rain or when its to cold. I do have a full hard top, that I hold on with C-clamps on the rails, the windsheild boltholes are still there. Have pulled it at Highway speeds like this and had no problems.
So it just depends how you use yours, if you want the top to seal real tight and fit properly, leave em, if its not a concren fill em.