there are better options now than the ZeroG. NegativeG, Ciamillo, EEBrakes, KCNC, TRP R960SL (and the soon-to-be-released R970SL).
Here is a comprehensive review of some lighweight brakes:
http://fairwheelbikes.com/forum/viewtopic.php?t=4289
Review of the KCNCs:
http://fairwheelbikes.com/forum/view...p?f=104&t=5057
Review of the EEBrakes:
http://fairwheelbikes.com/forum/view...p?f=104&t=5620