Are you talking about the AD700(x) (open back) or A700(x) (closed back)?
I have m80s and AD900s, which are similar in fit and tone to the AD700. They are very different headphones from the m80. The AD700 will not be portable, will not be usable in noisy environments, and will have considerably less bass impact than the m80. I find the audio technica headphones quite comfortable, but they are also very delicate in comparison to v-moda builds. I will say that I far prefer the AD900 to the m80 for everything but portable use and, occasionally, bass heavy genres. It is extremely detailed, with a great sound-stage and excellent imaging (especially for the price it can be acquired at). If you plan to use it anywhere other than around the house, I would look at other options. The JVC HA-S400, for instance, offers some similarities to the m80 at an excellent price point.
If you do go the AT route, the (x) models have reportedly improved bass response, although I have never listened to them.