I agree fellas, an Rc number by itself only tells us one part of the story, and could actually be very misleading. Different alloys, and different blade geometries will perform to their best potential at different hardnesses... maybe one shop's Rockwell is calibrated for a certain range and not accurate in the range you're looking for... What if the Rockwell machine hits a vanadium carbide, that would really skew your readings... OK that's a bit of an extreme example but I suppose it could happen.
I have all my HT done by Peters', and it's cool that they Rc each blade. That saved me a lot of frustration when a supplier (I won't name names except to say it wasn't Aldo, Tracy or Pop's) sent me a bunch of 416 labeled as 440C... Brad caught the difference (46Rc vs 59-60 like I asked for) and those 416 blades are in the scrap bucket, I didn't waste time and money finishing them. The other 440C and CPM-154 blades in the same batch tested right, and held up to my shop-testing... I have full confidence in them.
I do like Rockwell testing as a beginning point; but using a given knife design/geometry/alloy/HT the way it's meant to be used, then beating the snot out of it until it breaks is the only way to know for sure.