I have been using my frame as ground for over 6 months and it seems to work fine. I really like the simplicity of just running the positive lead where you need it. After having a over-complicated setup last year, I have moved to the other end and tried to make mine as simple as possible. My power switch is located on my underseat bag which holds my battery, so I only have one wire running to my front light and one to my rear light setup. So far, it has not let me down. I have an aluminum frame, steel fork, aluminum seatpost and rear rack, and the ground seems to work fine through all of these components.