Ill second what Kevin has to say, they do the work fast, real fast,
but there is a learning curve to them as well. I have a couple and
use them for very specific purposes.
Second is the price of the machines, some will set you back quite a
few grand. You'll want to experiment with media as well, what works
well in a vibratory, may do different things in a disk. Most CDF's
are either "wet" or "dry" only a couple can do both types of media.
The people I would talk with are the Otec people, probably the best
in their field of finish work, you can send them samples and have
them do test runs for you, and get their recommendations I would look
at the ECO line of their machines. The big thing is going to be the
size of your parts, and how many you want to finish, that will
determine the size of machine you would want to get.