Well it's opinion. The reason I like the classified is because it's 6 Phase PWM instead of the 4 that come with reference. Better non-reference design.
When it comes to the 570's the non-reference cards are the way to go.
For the 560 or the 580 either reference or non-reference cards are great and neither having any issues.
That's my take.
That was what I was thinking but posts like the one on the top of that link have scared me.