Separate X-Y Table or Rotary X-Y Table for CNC use?

First, let me say that I'm here mainly for the DRO stuff, but the CNC stuff
has been quite interesting.

Instead of doing a full CNC conversion to my Bridgeport, would it be
possible to buy one of those imported X-Y tables & use it for the CNC
stuff. (I have thought of a good solution for the Z-axis.) I've also seen
rotary tables with a little X-Y travel in them that would be a good start
to a 4-axis machine, but only for small parts. It seems like with the
smaller tables, the torque would be less, so smaller motors would work
etc. It seems like it would work - or am I missing something?