A word of warning: I installed 10.11 on a second partition, but having looked through the OS decided to wait this one out for now. On the understanding that I could remove the partition and resize Yosemite back to normal... It wouldn't let me... Tried everything, from Yosemite, DU back to El Cap's DU, all partition + and - buttons were greyed out. Tried Cmd R DU... buttons weren't greyed out, but the DU was El Cap's new UI version... And not knowing what to do. I ended up deleting everything... Suffice it to say, I had done a CCC moments before fiddling with the Beta, for such an event like this. And I am back up and running. However, if you are a little flaky on the inner workings of DU and/or trying Beta's out. My advice, install it on an external and not on a second partition unless you are confident, and know your way around DU and Cmd R. Toodle pip and tally ho!