I'm more concerned with reliability. I don't want my dirt-bike, which is going to be taking heavy shocks and impacts for long periods of time, to be dependent on circuitry the size of a red blood cell. If I can destroy a piece of equipment in my computer by poking it with my finger, I'm going to be damn scared when a similar piece is installed on my bike, and I fall down on a trail.
That's not to say it won't work fine. Indeed, I've bought a totally digital helmet camera without hesitation, but I still have a natural preference for mechanical, rather than electrical, solutions.