Best voice driver I ever used.
I was sorry to see them discontinued. You may want to try the Ademco voice driver. I've been told by old FBII employees that Ademco used much of their design. But that was a number of years ago. They may have changed it by now.
I've been using the Amseco voice driver as of late. It's VERY versitile as far as choice of outputs. It's ok but the FBII VS 279 was much stronger than the Elk or Moose or Napco units. I've got about a half dozen or so of the 279's left that I'm saving for replacements.