1. The bass is not -that- much. Definitely not underwhelming, but you shouldn't expect a heavy bass response. People have claimed that it improves vastly with amplification, I haven't tried amping them though so I cannot tell. Also, seal is -key- to the bass response. If you have relatively normal-size or smaller ears, it should be fine.
2. Durability is a bit of a bitch. They do pick up scratches easily, you definitely can't throw them around, I would even wager that you almost can't wear them on the street/ throw them in the bag. If you don't plan to travel them much though, or if you don't care about minor scratches that are only viewable under certain angles, you'll be more than fine. I'm actually looking to see if those scratches can be repaired through a metal-buffing paper.
3. The highs can be a little sibilant. Again, it has to do with your source, the quality of your music (these are really detailed headphones), and your amplification. If you have a good rig, they should be able to perform fantastically.
700 bucks is almost a steal. However, don't expect an effect like going from 128kbps mp3s to FLAC when buying these phones. The differences will be subtle. These are an amazing looking, superbly easy to drive headphone, closed for portability, analytic yet fun.. and you will probably worry about them too much to take them out, haha.
Hope this helps, if you got any more questions, I'll be happy to answer