For this drive, read the Liteon forum here, then decide!
BS0S is the latest "official" firmware, and it was improving - if you're worried about keeping in warranty, stick to that.
Semi-official (released & withdrawn) BS41 adds 1653S-type capabilities, without crossflash tweaking ... still waiting for BS42 to replace it!
Crossflash patching enable the generally much improved 1653S firmwares to be used.
Liteon's release schedules seem to be stagnant for the 1633S, dead for the 1213S (lowest member of this drive family), and the more interesting 1653S firmware seems to appear only on a foreign site.
For this drive family, new firmare is addressing the miserable performance they started with, giving acceptable burns on a much wider choice of midrange media. When previosly, it strongly favoured very few brands of the highest quality +R.