I had a set of those Barelli 280 cleats, the theory behind the stepped design was that it would stop you overshooting the pedal cage when putting your feet in clips. Can't say that I noticed any difference. What I did discover was that if the soles of your shoes weren't stiff enough, walking on the cleats would cause them to bend and close up the slot meaning that you had to prise them open before being able to remount.
187 cleats were similar but unstepped, whilst the B10 cleat were specific to the B10 pedal.