I have received several Beta releases from Cisco SMB level 2 support over the last year, but only when I have an issue that they know (or think) will fix the issue.
In order to obtain Beta releases call Cisco SMB, describe your issue, and ask if there is a Beta firmware available. The Cisco techs that frequent these forums are really good at replying to older posts describing outstanding issues that newly available Beta firmware might address.
Hang tight.