Several other things I neglected to mention. I believe Tony has used CPM-M4 (not stainless) also and has made knives using carbon steel as well as CPM-S30V (and many others).

All these steels are great. Keep in mind the most important thing when it comes to the performance of a blade is the heat treating process. You can either make or break a blade by heat treating.

Tony and Reese can I am sure give you their impressions of each of the steels that they use in more detail then I can.