Running Plex on a ReadyNAS Ultra Plus?

iMike74 wrote:
As RAID-backup isn't so important to me

There is no such thing as RAID-backup. No form of RAID provides backup. RAID (except RAID-0) provides redundancy or high-availability, not backup. If you primarily store important data on the ReadyNAS backup that data regularly: Preventing Catastrophic Data Loss

iMike74 wrote:

In the guide it's recommended to get the ReadyNAS Pro 6 if you want to handle HD material as you need a very fast processor. When looking into this it seems that the Pro6 is armed with a Intel Core 2 Duo 2.8 Ghz processor, while the Ultra Plus only has an Inten Atom 1.8 GHz processor (with a dual core). I don't know enough about processor performance to judge how much slower the latter would be, so I need to ask here.

There is no comparison. The Pro 6 is way faster. If you want to transcode (i.e. convert on the fly) video to stream to an iPad get the Pro 6. However if you just want to stream (not transcode) video e.g. to a Mac, then I think the Ultra 2 should be fine.