I used to whip them as well, but I found that jumping this way was actually safer. Sometimes my whip-timing was flawed, sometimes my positioning wasn't perfect (one pixel too far)... This way is safer in that the path of the spider-jump and the path you jump are almost exactly the same, except for direction. This gives you a very large time-interval for correct timing. Also, the intensity of the spider jump doesn't really make a difference, because the trajectory doesn't diverge much when the spider is still close to the ground. Oh, you should aim to end up above the spider though, so you don't meet it by going sideways.
I find it quite hard to put to words why this method works so much better. Perhaps an epic paint production might help clarify:

... though I must admit that I just felt like painting in paint. Perhaps the best method to convince yourself is to try it. (Or someone should show me how to properly record stuff?)
F