There really should be differnt stages or types of beta testing though, bug hunting is one thing but my impression is that PDS is interested in ideas, suggestions and feedback from players as well, and that might be more difficult to do if you're flooded with "casual" testers? Maybe it ought to be either two separate groups of betas or the "flooding" should only occur in the later stages? I guess that's what most companies do though, like I preordered StarCraft II and got to play the "closed" beta but that sure as hell had nothing to do with influencing the game making.
I think that you are right about that. Right now I really need to make sure that this (and some other) theories follows reality. I will try several different models to see what works best for different kinds of games.