Sorry ieee488, it's not my intention to hijack your thread, but this is of great general interest, so I hope you don't min if I post some more information related to this topic.
Yes I undertand. But others maybe need to be able burn DVD-RWÂ´s at 2x burn speed.
Okay, I tried two diferrent discs, one burned once before and one brand new.
Both are with MID; MCC 01RW11n9, 2x rated. After a burn on BenQ 1620, none of them can read back by any of my DVDRW drives.
You can see my burn on BenQ above. Just to prove a 16x burner is able burning 2x DVD-RW I will attach a pic. from NEC 3500 burn.
Picture no. 2 proves once again, BenQ is fully able to rip (read back) 2x burned DVD-RW. ~2GB data was read-back in less then 3 mins to my HDD.
I have to do more testing, also on other firmwares, before any final verdict can be made.