So you really can push a SATA2 disk into a SAS backplane?
Solution 1:
It works. SATA discs are compatible with SAS. I have tons of them in SAS backplanes. Work like a charm.
Solution 2:
Yes, difference: SATA devices contain a gap between the power and the data connectors, while the SAS devices do not. Meaning: You can connect a SATA device to an enclosure that supports SAS and SATA, but (hopefully;) not the way around.
Solution 3:
You should install an interposer board between HDD and the backplane in case you have problems. See: http://www.knowledgetransfer.net/dictionary/Storage/en/SATA_interposer_board.htm