I'd suggest something bound on the actual customer account in the CS profile view where I've downloaded all my purchased things so far.
They could mark it as "beta" or "in development", open a separate thread for input and comments on it and everybody would be good to go, I think.
An email based distribution between people isn't the appropriate way in my eyes. Don't see this sentence referring to you personally though, I appreciate your work.

So, if there's something official to share (which could be beta testing too) on the B-52, make it official, that's my point of view here.  :)
As you see, we've just stumbled into the fact that there is some B-52 development going on because jbntx mentioned it. Otherwise, nobody would know.