Ok, fair enough. I guess the betas you release have to be stable enough so that the feedback you get from external users is meaningful, and not along the lines of "Where did my hard drive go?"
However, does this mean there another nine month cycle before feeback from a wider group of beta testers is incorporated? Or is this particular case unusual?
Have you ever considered using a "Stable/Testing/Unstable/Current/Frankly we are suprised it even compiled" type scheme?
Some of us are still using Win2K as it has been patched enough to be truly reliable, and any little quirks with particular apps are well documented. As there is no official 'Stable' version of Windows though, the only way to find the most reliable version is
to see which has been around the longest that still does what you need.