Sentinel questions potential new user

WD Legacy Products Sentinel Products
4

The 4200 does not have the remote file access built in.  The DX5100 is probably a closer replacement to SBS.  All of these are Windows boxes which give you the most file access control.

A qnap/*nix* box may seem simpler because face it, a free operating sustem does not do as much as windows.  For ease of use it is hard to beat a Pure NAS box like the ones you mention.