I should say that I also use the Zeros. They are MUCH stiffer to get into than the Light Action or the X series pedals. They take some getting used to...for the Zeros, I found that gettting used to clipping in was significant (as OMS said...it was interesting to figure out how much pressure to exert to get into them!). At first, it feels like your feet are on little patches of ice...sliding about because of the float. The great thing about the Zeros compared to the other two series is that you can manipulate the float...even locking it out so that there is no real noticable float. The other two types have a set amount.

I am a Speedplay gal for sure, so I will endorse them till the cows come home. I do have to get some new shoes though. I use Sidis on my MTB, and they are SOOO comfy...so I'm leaning towards picking up a pair of them for my road!