The Dynomotion stuff works as advertised, probably better. I've got a 1994 Fadal 4020 retrofitted that will move smoothly at about 3X the factory acceleration, and has no problems feeding accurately even at full rapid. I think you'll really enjoy it, given your background, Al.
I'm using KMotionCNC, the control software that comes with the board. I don't know of any reason to use Mach instead, but I might be missing something.
This is a video of the machine running that I took a long time ago with the table mounted camera (hence why the table isn't moving relative to the camera). I don't have it running at full speed until around 2:30 or so
"http://www.youtube.com/watch?v=ZOfzLbodL_8"]1/2" cutter,6061-T6, FSAE chain ring - YouTube