I have a Asus DRW 1608P3S and its 2.5 years old. It has problems in closing tray(Have to push the tray to close it) but this problem is acceptable. The main problem is whenever I insert a 16x DVD-R (any brand) it sometime detects the DVD-R as 4x media and after reinserting(sometime restarting the PC) the same DVD-R again(sometime 2 or 4 times) the drive detect it as 16x media. As far as I know the MIDs of DVD media are stored in Firmware of the DVD-RW drive and thats how the DVD-RW drive recognize the DVD-R as xx speed, if no MID in firmware then 4x is default for my drive. I have the latest firmware and all the MIDs of used DVD-R are in the firmware (Sony16D1,MCC03RG20,MBI01RG40,CMCMAG.AM3).
Mitsubishi DVD-R 16x detected as 4x
Mitsubishi DVD-R 16x detected as 16x (same disc)