Tastes will vary, and trying not to sound argumentative here, just because somebody doesn't have many different headphone experiences might not be the deciding factot in how well they detect pleasant versus unpleasant sound. It is quite conceivable that somebody could have years of experience with many different headphones and just have bad or sensitive hearing. I have been listening to Grados' for years, and yes without much doubt they are bright headphones, but they make it work well all things being considered, plus there are some rewards realised by such a sound signature. Back to the 770s, I own a pair and I do not find the treble fatiguing or overly bright. For certain it is prominant, but so is treble in live music. For me the real test is it pleasant and musical in it's presentation? Does the treble make you want to stop listening or does it sound right to you?
I think the trouble with graphs are they only present the least relevant information, they omit how an individual's brain will ultimately experience the sound which is the only measure that matters. Yes I realise there is a great deal of similarity between people, we're more similar than we are different, but a vast amount of ancedotal evidence suggests that even small personal differences can result in big perceptual differences in everything, not just sound perception. All I can say is that I listened to some very well recorded, very demanding music with plenty of treble information on the 770s and I do not find the treble to be anything but very pleasing, engaging and musical. How can two people see things so differently? Nobody knows and nobody should act like they do, we all are different. If you vastly prefer warm, less forward headphones you might indeed find the treble energy less than ideal, who knows? I personally find the 770s to be far less forward in the treble than even my HF2s, but that is just a perception, I can't guarantee you that beyond a doubt you will agree with my view. I hope you have a chance to hear the 770s for yourself.