[Al Skierkiewicz]

I need to remind everyone here that while it is good to talk about designs, rules do change from year to year. I caution you to wait until the game is revealed before locking into a design.
That being said, I tell teams that you should never depend on the attachment hardware to be the mechanical basis for your bumper design. Many teams that use the attachments you show in the drawings above, have considered the forces involved in robot to robot interaction and designed the mounting such that bumper forces transfer to the frame through contact with the frame not through the hardware. In your first render for instance, if the brackets were such that the frame held the brackets in place and the hardware just kept it from falling off, that is a good design. In the third render, it appears that just gravity and the hardware keeps everything in place. If the other robot bumper system is lower than yours, the resulting force will force the bumper up and off the frame, leaving you with a bumper dragging behind you or left on the field.
As far as reversible bumpers go, I think they are a good idea when designed properly. I have said many time before, if you go to great lengths to make a beautiful robot, why would you put bumper covers that sag, drag on the floor, open and show the opposite color, etc. I am a proponent for bumper covers that do not have parts that sag outside of the bumper zone.