I will not keep you waiting, the winner is easily the Thecus N5500.
Started out purchasing the Drobo FS with high hopes it would suite all my needs. Well first pitfall which was a deal breaker is there is no Active Directory or LDAP integration. Drobo support says this is because they are targeting the small office. I call Bull Sh#$, plenty of small offices have active directory and are using small business server.
So back the Drobo went and I ordered the Thecus N5500. Once I got the N5500 I dropped in five 1TB drives configured in RAID 6 and away I went. The web interface is great and setting permissions on folders is very simple. Performance is good and I expect it to even be better once I setup link aggregation.
So far the Thecus N5500 has done everything with ease I have asked of it.