I have been trying to make the same decision as netmage but I see the answer as being much more simplistic.
As human beings we are always striving to make things easier and more comfortable for ourselves. Once we become comfortable and happy with our own abilities and those of the machines/tools that we operate we tend to relax in the knowledge that everything is fine. This is when we take our eye off the ball. It can happen at work, on the sportsfield, on the road...if it happens in an environment where we need mechanical intervention to merely survive, the outcome can be fatal.
Eccr's fly the machine and allow complacency in the total reliability of the unit, mccr's force you take control of your own actions on every dive.
It cannot be a coincidence that there have been no fatalities on mccr's?
(ok, now that I have lit the blue touchpaper I will retire to a safe distance!
)