Your firmware is MYS2, so MYSx (recent: MYS4) is the right version (scroll down on www.sonyisstorage.com). Sony is confusing me here, because any information they provide for my drive (DW-G120A-BR, "Sony"-logo on the frontplate) indicate that this should be a retail drive. But the firmware, the drive came with, was also MYS2, which is a version for OEM drives
If voiding warranty doesn't matter, this drive can be crossflashed to Liteon SHM-165P6S, if I remember correctly. In that case, you should search the Liteon/Sony forum for further information.
(sorry for digging this old thread out )