I agree to keep the shape if possible (should be), the wire is probably more expensive than it has to be (and that jacket does kink easily), also Velour Earpads (I like Sennheiser’s microsuede on the HD 800 and 800 S, but never liked the stock HD 700 pads), more realistic price of $400.
I’m wearing a pair of HD 700 with Dekoni’s Velour Pads right now, they already to a lot in making the sound more cohesive, sounding even better integrated than the less squiggly lines on their published FR Graphs suggest. I would have to look it up again, but I believe the HD 800’s treble peak is even higher than the HD 700’s, but because the rise is gradual rather than coming from a dip the HD 800 is easier to digest, stock. My ears are treble sensitive (can’t listen to Beyerdynamics for long), and this HD 700 + Dekoni Velour sounds like it’s still on the right side of treble being balanced between too little/too much. Having Sennheiser’s engineers look at the treble again and see if a bit of treble absorption (or some of the HD 800 S’ tech improvements over the HD 800) makes sense wouldn’t be a bad idea, but it may not be strictly necessary if it would hurt the detail/soundstage of the HD 700.