I have not posted in a while but I think that a quick update is in order.
First, I recently tried the S700 again. By now they have been used for countless hours. From a brief three minute listen, I felt that they actually did open up a bit. To my ears, they sounded much better than I remembered them.
Second, I sold my ATH-ESW10JPN after about three weeks. I just thought I was crazy for spending so much on headphones when I was perfectly happy with the ESW9. Makes sense, right? I agree but within a month I had another set of ESW10JPNs in my hand. Honestly, I just couldn't bear to be apart from them. They are head and shoulders above any other portable headphone I have ever tried. I felt that my best bet to save money in the long run would be to buy one pair that left me so satisfied that I would not have to keep wasting money on new headphones.
Having said that, while the ESW10JPN is amazing, I think that the ATH-ESW9 or ATH-ESW9A (the US version) really hits the sweet spot in the line-up. The ES7 sounded very good for a $100 headphone but I felt that the ESW9 was so much better that to me it justified the $150 price jump above the ES7. However, no matter how amazing the ESW10 sound and looks (and don't get me wrong - it's AWESOME) I see absolutely NO WAY that it justifies its price being $250+ more than the ESW9. It sounds better but not nearly that much better. Having said that I would never give mine up again. Also, as of this writing, the ES7 costs about $110, the ESW9 about $265 and the ESW10JPN about $530.