The problem is not the holster. The Serpas are just as sturdy as any of the other holsters out there. The was a lot here say about ADs from the Serpa system. Yes, they are not dummy proof, if you have your finger on the trigger and try to re holster, you're gun might just go off. This is kind of like blaming a Glock for an AD.
I have the QD system and was a little worried about the strength of it prior to buying it, after looking it over and using it I have no worries. The holster will break before the Quick Disconnect will. And as for someone walking up and being able to disconnect it, the TWO release tabs are so small and hidden it would impossible for someone to remove unless you were asleep. This shouldn't provide anyone with a false sense of security, practicing gun retention is crucial when OCing.
As for "Special Ops" types having ADs with the Serpa system, I can't find any credible evidence of this happening. What I was able to find were testimonials from ex SF guys working as private contractors that have used Serpas over in Iraq and Afghanistan without any problems. I do know that my dad who happens to be an ex Green Beret has been using one for a couple months and really likes it.
I don't think the system is perfect, my guns do tend to show an awful lot of holster wear when compared to other holsters, but I think its a decent trade off for the ergonomics of the holster.