I bought a Contour and don't use it - here's why:

1. The footage makes riding look more exciting - I don't want exciting in the event of an incident. I think it's the wide angle lens and the shaking of the camera - but passes look closer than they really were and speeds look faster. I think camera footage is likely to make me look more negligent (at least my contour).

2. More weight on my head - I already have lighting up there and it starts to get annoying.

3. Unlikely to get a readable plate in hit and run. I have to be looking JUST RIGHT.

4. One more thing to keep charged.

5. Attitude of LEOs - in my area they're "funny" about being recorded and there's an implied question of "why are you doing something odd" and an assumption of aggression on your part. I think other people feel the same way.

6. It's another thing I have to carry around once I park. I can't leave the helmet with a camera on it.