There should be none of the older ones out there, unless you buy a used stove. Anything new in the box was sent back to Quad during the last "Quality Hold" and they updated them all. The boards have a sticker on them with the revision, but I can't remember the newest one.
My Mt. Vernon AE was manufactured 4/08 and is has the latest controller Board Rev C my dealer confirmed this when the stove was delivered. I have about 4 hours on this stove with no issues we will see what happens in the fall.