I don't whip-skid so I can't say. But in my 8 or 9 years of riding clipless (been riding clipless fixed since 2002) I can't recall unclipping unexpectedly. I've ridden SPD, Egg Beaters, and Time with time being my favorite of the 3. I pull pretty hard on the up stroke (something that's hard to do with toe clips) and I've never pulled out.

I can't imagine you clipping out on a whip skid. If you are worried about it, get some pedals that provide some positive resistance before disengagement. To explain: Some pedals provide a "wall" that you feel when you are about to clip out. Imagine bending a #2 pencil with your two hands till it snaps. That snap is sort of what it feels like to unclip. Some pedals don't provide that wall which sort of feels like bending a hollow Bic pen...just bends till it's bent. You just simply twist until you disengage (Crank Bros Eggbeater, Speedplay). I prefer the wall type (SPD, Time). But that's a personal thing.

On a related note, I'm going to buy some Ultegra SPD-Rs today for my track bike (for actual track use).