Another post with similar subject matter:
From what I've read and based on my own 1620 experience, it simply varies from drive to drive to media to media. I would disagree with jamescooley1's comment about all 1620's being the same as far as firmware goes. Just browse through the benq forums, and you'll see why.
Also, when you have time, browse through the "post your _____ scans" threads. I'm sure you'll come across MCC 003 (for sure) and some Ritek/Ricoh scans. May give you a target point to consider for your drive.
To add to that, you can always try your own mad experimenting ... MCSE modding write strategies and such. Gotta luvit!!