Ok guys, here is the deal as I have understood it and witnessed personally with my own bows (both binary cams). With a drop away that ties into the down cable. What happens is, the cord attached to the cable gets taught at full draw. Most manufacturers suggest having the rest up at full draw the 1-2 inches of the the draw cycle. What this does is actually pull on the down cable and causes a shortening effect on that cable. Guess what it does to the cam its attached to. It retards the bottom cam.

I believe the limb driver website shows you what happens with the cable pretty clearly, though in their example its a bit extreme of what I've seen personally.

The thing I'm starting to realize more with drop aways is that you want that rest to stay up for as long as it can, then get out of the way to clear your fletching. This is why standard drop aways recommend being up the last couple inches of the draw cycle. The problem is the cable distortion.

The Whammy and the limb driver do not suffer from this effect. They're both not attached to the cables in a manner that applies pressure to them. The Whammy, is connected to the up cable and at full draw, is slack, not applying pressure. The Limb Driver is not attached to the cables at all, but the upper limb and is also slack at full draw.

I know from personally experience that the Whammy really does do as advertised. It stays up the entire time until the very last second. It's then jerked out of the way by the up cable advancing downward. Then it resets itself in the up position. It's so fast, you'll never see it actually happen without video equipment.

I think these two rest in particular are way ahead in drop away technology at this point.

To answer the question about the Zero Effect. This is one rest that I don't see how it can affect timing as well. The slide is free to move naturally on the guard so it shouldn't have any ill effects.

Keep in mind that the effects of the standard drop aways probably is minimal in most cases. What you'll see is a drop in let off. If a bow is 80% and the rest is setup per manufacturer suggestion, you'll likely be only able to obtain around 65% or so without twisting your cable to restore let off. If you'rea tuning feak like myself, you'll tinker with it till its right.