I actually see no reason to use Dedupe Friendly when you land you backups on a ReFS repository. The recommendation would be to create a full backup there first, then incrementals with synthetic full in between (as Gostev said, once a week is used a lot).
@HendersonD: I misread something yesterday. We do advice to leave storage-level corruption guard on. It might look like overkill but hey... They are your backup files
. Only when you run it in S2D or classic storage spaces I think it is not needed