I'm having severe issues using tvOS storyboards with XCode 7.1 beta. I've tested this with a brand new project and I can essentially cause 100% hangs by dragging a viewcontroller into the storyboard. As soon as the view controller icon is dragged over the line to the storyboard, XCode hangs. The weird thing is that this only happens on my iMac - everything appears to work ok on my laptop. I thought this was because the laptop was using El Capitan, but after upgrading my desktop, the problem remains so clearly that's unrelated.
In addition to frequent hangs, doing other things results in crazy slowdowns (such as moving a view to its parent view).
I've tried with a different account (brand new one) and the problem persists. I'm installing the GM Candidate (which I thought I had downloaded, but didn't - ah well), to see if that improves things.
Is anyone else seeing this issue? I swear everything worked fine until I started trying to add additional view controllers.