The three blades I had rehardened came back exactly how I sent them, no warping etc, dead flat straight just like how CRK sends them out. Edge was perfectly fine, but dull. However you will loose that beautiful stonewash finish.
Me..........
And yes, if Paul Bos thinks rehardening (at least just once) is ok, then its just fine. I used those blades for years and the only difference I noticed was no edge denting, keener sharpening and much better retention! I'm quite happy CRK made the bump and personally in day to day I absolutely notice the difference.