Quoted from: http://www.catchfence.com/html/2005/mt111005.html
... It struck me that a SFI certification is valuable to a degree, but, that it's not truly a performance measure. It is, in fact, an endorsement, but, it's an endorsment that a particular piece of safety equipment will do a particular thing under a particular set of test conditions."
"So, it struck me that the defined test protocol was wonderful in terms of repeatability, but, SFI tests are so narrowly defined to be repeatable, that
the point becomes passing the tests at, potentially, the expense of performance out in the real world under real conditions. The simple fact of the matter is, an auto racing incident is a massively complex situation. The kind of crash, for example, that I might be involved in in my racing car on a road course is going to be very different than the kind of incident I might be involved in in that same exact car at a performance rally out in the woods."