I used G05 once and was not satisfied with the (scan)result, so I avoid them in the future. The disc (recorded at 4x) however played fine. In your case I would upgrade my drive crossflashing with CS0T. Use this firmware: http://codeguys.rpc1.org/firmwares/dvdrw/1653S.CS0T.patched-cf-mcled.rar
If you want to be able to return to BPSA, backup your firmware first, using LtnFw (tools thread). And always a good advise is to make a backup of your EEPROM with the EEPROM-utility. You can use this tool also to clear the Learnt Media, making a fresh start with the new firmware.
Be aware, with crossflashing you may lose your warranty (if still valid :disagree: ).