When it comes to safety the biggest component is the driver and the second is luck. If you are paying attention and driving defensively you have less chance of getting into an accident. Freak accidents occur and that is where luck comes into play, if its your time, its your time.
Also, most head on collisions I've seen have been at higher than a net 40 MPH. They are more like 2 cars on the interstate or back road doing 55 + MPH, so you'd be just as dead in an H2 as a smart. Not that I have any statistics at the ready on this, just my observation...
I'm not losing any sleep over this...