We're hoping that HifiMAN will produce a HE-700 model. Perhaps that would be something to strive for?
With the HE-700 model, we'd hope for them to strive for: planer driver manufacturing to be more automated,as they've done with the HE-400 to keep costs done. To work on frequency spikes and tame some sibilants. To keep the efficiency of the headphone in the range of the HE-400, if not improve upon it. To offer it in another color - possibly a hammered bronze finish, as I've performed in the past on the X-LS monitor speakers that I posed pictures of a few weeks earlier.
Any other wishes for the HE-700? I'll gladly type up a summarized "wish" list and propose it to Dr. Fang. Granted, it may not go far, but progression at the least is worthy of presenting the question.
Make it happen wje.