Peters is really good on complex stainless and high end tool steels. The only negative is that they are a professional HT company, and are not price geared to a small one at a time maker. They charge $25 for a single blade, but charge $100 for twenty blades. $25 is worth it for the job they do, however. They are fine with doing oit, and your blade will get the same attention as any big volume maker does. You can also send it over to another knifemaker who uses Peters, and have them toss it in the next batch they have going out to Peters. That way, it will cost $5-$10, plus a few bucks in shipping back and forth. It all depends on how much of a rush you are in.
CPM-M4 gets HARD. I would do a slicer at Rc 62-63. Just tell Peters that is the final target, and they will take care of the rest. I have done CPM-M4 large fillet blades at Rc64-65, and could not see any additional advantage. You will need a set of DMT plates to do the final edge, or you can use a grinder if you are set up for VS. I prefer stones/plates. Two 3X10" Duo-sharp plates and a holder are very affordable ( around $139), and will last forever if used correctly. That will go from X-coarse to fine.
