I bought these pedals to go with the Sidi Sierra shoes. I wouldn't recommend these pedals for that setup. The fit was very weird. I'm not real experienced with the clipless setup, but I would definitely go with the eggbeaters instead if I were to do it again. The plastic just seemed to get in the way.
I can see, however, that these pedals might be good if you were doing more of an enduro type of race.