I found the "Hi-Res" badge on my HD 600 box a bit amusing, since it's on a headphone from 20 years ago, not some new, mondo expensive four figure flagship. It'd almost be better if they didn't certify older designs from a business perspective. Make people think that the badge actually means something and that they have to spend megabux in order to obtain equipment that carries it. Personally I'm a lot more concerned with what the response between 20 Hz to about 18 kHz looks like, since that's what I can actually hear, and above about 22 kHz is where all my music taps out, anyway.
A much more useful certification would be for headphones whose deviation from a standard target curve is less than +/- 3 dB, with some grace given for bass and upper treble extension (open dynamics all have trouble with the former, and the latter isn't easy to measure). Of course that would require having a standard curve everybody agrees on, which won't happen anytime soon (if ever), but some variation of the so-called Harman curve (it has a proper designation now, but damned if my Google-fu can turn it up at the moment) would be a good place to start.