My $.02 (I've owned Q701 and HE-400)
I can't remember if my Q701 had 7 or 8 bumps, but the bumps didn't bother me at all. Comfort is a personal thing and some people can't stand the bumps, but I have no clue what they are talking about. I have short hair too. The Q701 is a very lightweight and comfortable headphone IMO.
I also find the HE-400 to be perfectly comfortable. It's a bit more than twice as heavy as the Q701, but it honestly feels even heavier than that in the hands. On my head, though, I don't notice at all. Again, that's a personal thing. The HE-500 is even heavier.
Sonically, the two are very different. I prefer the HE-400, but that is because I mostly listen to electronic music. The HE-400's strengths (fast, powerful bass, aggressive rendition of textures and details, separation between sounds) make it excellent for electronic music. The Q701 is less visceral. Its bass is deep, but it doesn't have anywhere near the impact and physical presence of the HE-400. What the Q701 does better than the HE-400 is reproduce a large sense of space and more natural midrange tone. The Q701 beats the HE-400 for acoustic, classical, and most genres with real instruments. For rock, I prefer the HE-400 because it puts more energy, bite, and crunch into electric guitars, and it makes drums sound more like real drums. But the Q701 is decent at rock as well, especially lighter rock. The National, for example, is great on the Q701. I don't like the Q701 for electronic music at all, except for ambient.
Word on the street is that the HE-400i is supposed to have a warmer sound than the HE-400, closer to the HE-500. The HE-500i is supposed to be more bright and aggressive. But this is mostly speculation. The HE-400i and HE-500i are going to weigh less than the current Hifimans.
EDIT: I just remembered the "HE-500i" is called the HE-560 in reality... Oops.
Edited by manbear - 4/3/14 at 11:09am