Our limited experience with DSS as NAS in a Windows environment with a large AD has followed a similar path - struggled with it for a while then gave in & used Windows server/s as the NAS. The posix rights was sort of ok (just), but system hardware instability meant the link between user accounts & directory rights got confused more than once, & meant some stressful work to correct! There is now the ability to back & restore this mapping, and quotas too, but I'm not that confident. In simpler situations (simpler rights) I think the NAS function is just fine.