Thanks, maybe I can get a used 840.
The Netstor is a bit over the top for me as I could get a WD Mybook Pro as well including Drives (non-SSD) however for around 600€ for 6GBs.
But does your suggestion mean, I could for the time beeing only put 2 drives into a 4 drive enclosure? I.e. the Akitio Thunder2 Quad (which has a handle )
The would leave the option to move to RAID 5 at a later time.