I've been using a feather in my fatboy, which i think is ideal, since you can just adjust the blade exposure. no nicks/cuts to speak up and i set it on a 5.
These threads are pretty interesting to me because I seem to have taken to Feathers like a duck to water. I found that because the Feathers are so sharp, it's easier for me to maintain correct technique and therefore I cut myself far less often; in fact, I've probably only had three or four weepers and maybe one nick in about a hundred or so shaves with Feathers.