2 Bay DAS or NAS?

Hi

I have been looking at loads of your excellent videos and I am still unsure what to get. I currently run a 4TB WD external USB drive and 3 portable drives to back up my Movies and the 3 portable for Photos, Time Machine, and complete iMac Backup. I use Carbon Copy Cloner to do all the scheduled backups. I was going to get a 2 bay DAS but getting mixed reviews on reliability on all of them.

My iMac is a late 2013 21.5inch model with a 1 TB hybrid drive, Thunderbolt 1 ports and USB 3.

I would use the DAS/NAS just for backups and Plex to my TV across the LAN I have in my house. So my thinking was I dont need or would probably use a lot of the features of a NAS but like the network attached element. To be fair I leave my iMac on most of the time so a DAS does not present an availability issue in that respect. Transcoding would be preferred to future proof it but as I dont have a 4k TV I am more than happy with 1080p HD at the moment.

To me a DAS, which one ?, would make sense for ease of use but I am torn so your advice would be much appreciated and recommended models or either

DAS option is quicker because it connects via USB or Thunderbolt unlike 1GbE LAN (around 100MB/s). But most importantly, you don't need to remember about regular backups. All backups will be done just like Apple time machine/ time capsule. With a 2 drive system, you also get all your data to keep on two disks rather than one. This keeps your data safer.Simple NAS like DS218play would allow you to back things up and also allow you to stream locally and also remotely.If you need something future proof then DS218+ and DS718+ will allow you to upgrade RAM memory later and add extra disk. But it costs more.I hope this helps.