Yeah it really would be better to give developers access to the alpha version, since we'll have to basically rush updates once the beta goes public
Not realy?
Thats the whole idea of a Beta test... to give people the opportunity to test and make fixes needed... so when the gold release gets pushed.. your up to date for that.
Honestly, even with XenForo being as high quality as it is, people shouldn't be running beta versions unless they can debug and fix code themselves... if you don't have the ability to do this, you should wait for gold release and the subsequent addon releases...