I'll be really bummed if Karma has much impact on beta choices . I lurk much, post a little, but I'm not out looking to karma whore.
But, hey, if it'll help, I'm a Stardock customer from way back. I bought the original OS/2 Warp version of Galactic Civilizations...
I think you might be confused between the original (and still unchanged AFAIK) plan for public beta 1, for which a pre-order is the only qualification, and the 'pre-beta' or 'beta 0'. Recently, Brad posted some scraps about this selective 'pre-beta,' indicating that it will be focused on online features, especially server-based AIs. They apparently want a smaller pool of volunteers who seem to be a good fit for what they want to hammer out before they releast the first full beta to all us pre-order folks.
Probably, you only need to worry about the 'karma factor' if you're very interested in the online features and getting to give feedback on them as early as possible.