Russ Rose, coach of the six-time NCAA champion Penn State women's team, is not fond of the pancake dig. In the first place, he doesn't think it's a particularly good way to pop up a hard-driven volleyball. Secondly, he says it's hard to tell whether the ball has hit the floor or the back of a player's hand, which means that even if you make a good pancake dig, the ref may rule it a kill.
Russ isn't black and white on this issue, though. As he notes in the video, it's good to keep on open mind.