Are you sure about the BS4x and CS0x firmware being the same with a different drive name? I mean, it that's all it was, what is holding them up from editing the firmware and posting it? Are you sure the 1633 and 1653 hardware are identical? If not, then the different firmware likely addresses the hardware differences.
It's just not logical that if a simple hex edit would convert the CS0x firmware to BS4x firmware, why the delay?
Meanwhile I read in other BS41 versus BS0x threads that some 1633s work fine with BS41 and others don't. Perhaps there was a hardware difference between production runs that make some quirky for 12X DVD-R and 4X DVD+DL? I haven't flashed mine yet to BS41 since I do little DVD+DL and otherwise use only DVD+R...