Hi mate which Synology NAS do you run as I'm in a similar situation to yourself as I currently have a Mac Mini 2009 with 8GB RAM running Plex media server and home theatre from content stored on an external Western Digital 2TB Firewire hard drive so looking at something that can take the 2TB Firewire hard drive's place and leave everything else as it is as the drive is nearly full.
I don't think I'll need the DS415play as the Mac Mini will still be used.
I have the DS411j, so that'd be equivalent of the 414j in the current lineup.
