Erased my Sierra boot drive completely, then installed HSierra beta (6, I think, anyway about 10 days ago), choosing APFS specifically for the format, then the macOS beta install.
Restored apps and files from backup.
Ran Boot Camp then, and no problems at all installing Win10. As always, had to format the partition that was created by Boot Camp before the Win10 installer would use it --- but that's no different than what I have seen since using Win10.
So, in my experience anyway, a new Boot Camp install on a High Sierra beta system worked first time with no problems here.