Yes, because you have a but, although the Trackball Works software makes it possible to assign functions to the countless 4 buttons trackball, features highlighted as are the modes and Digital Zoom are NOT SUBMITTED AND SUPPORTED IN NO EVENT (no "trick" can to make them operational) on Mac OSX Mountain Lion / Mavericks (not tried with other versions). It is unacceptable that Kensington does it report anywhere even while in their FAQ they indicate black and white that the Mac drivers manage these capabilities.
But hey honestly I do not care whether they are implemented in a future upd drivers, I use the trackball to work and have no need of these features gadgets, but prevents it remains false advertising, while Simply ...
In summary, this is a great trackball from my point of view, but if you were interested in Digital Zoom mode and on Mac OSX, go your way.