Uh
Going from SAS to SATA is NOT upgrading, it is downgrading...
To the best of my knowledge, you can put either SAS or SATA drives in the Sanbloc S50.
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Speaking of which...
I have a very nice Sanbloc S50 with 12 x 10K rpm SAS drives, and includes the very expensive SAS HBA card for the Snap Server head unit (4200, 4500, 510, 520, etc) and the SAS cable. I would be willing to part with if there is any serious interest out there. This is a complete turn key setup. All you need is the Snap Server (and for the right price, I could include one of those too).
If you are serious about wanting it, send me a PM or email.