http://lmgtfy.com/?q=serpa+accidents
At some point "operator error" crosses over into "design assisted operator error" which simply means that the device's design encourages operator error, which boils down to "bad design".
At some point you have enough data points where you stop blaming the operator "It was user error! You need to practice more!" and start thinking, hmmmm, there have just been too many "user errors".
Given the holster being banned from some firearms schools as well as the growing number of "incidents" I think the Serpa holster has crossed over into the "design assisted operator error" region.
This of course is my opinion, and you're free to form your own. I just bought a
Safariland 6377 holster and like it a lot.
O2