Please figure out a way to have both live and beta versions of the client installed at the same time, and have the login screen choose which to use. More people would be willing to playtest without the hassle of uninstalling and reinstalling the game every time they want to switch servers. You should also disable achievements on the beta version.
These are both good suggestions, and the achievement disabling is something we're actively working on (and may even have a fix for coming down soon). I can't speak to the main suggestion but I like it
