I just installed macOS Big Sur Developer Beta 9. I have never seen a macOS go this high with Betas. Perhaps Apple has heeded all the criticisms of early (and even later) releases of Catalina. I event think there might be another Beta update before the October release of Big Sur. All seems fine in this new release. It is still very responsive, my main workflow Apps seem to work well enough. I will keep you posted on further Big Sur developments.