This subject doesn't seem to be covered very often since everyone is in 16x dvd heaven 
Here is a recent burn/scan of a 488mb CD-R disk while using the B7T9 firmware:
General Information
Drive: BENQ DVD DD DW1620
Firmware: B7T9
Disc: Data CD (Ritek)
Selected speed: Maximum
C1 errors
Maximum: 24
Average: 1.21
Total: 4041
C2 errors
Maximum: 0
Average: 0.00
Total: 0
Jitter
Maximum: 10.9 %
Average: 7.65 %
Scanning statistics
Number of samples: 3307
Average scanning interval: 1.01 sec
Glitches removed: 0
Now to me when I see that 4000 number I immediately think something has gone horribly wrong. The media is rated at 52x so the drives maximum of 40x isn’t a problem.
Also I am wondering if it is normal for the green led to always stay on when a disk is present in the drive?
While lurking on these forums I made my decision of buying this drive. I have to thank all of you once more for such a great place to congregate and talk about drives. This drive was a OEM so you also helped me flash it to the latest firmware.
Edit- Doing a burn on some CNC magnetics it makes my Riteks look perfect... Check this out:
General Information
Drive: BENQ DVD DD DW1620
Firmware: B7T9
Disc: Data CD (CMC Magnetics)
Selected speed: Maximum
C1 errors
Maximum: 56
Average: 8.94
Total: 29805
C2 errors
Maximum: 0
Average: 0.00
Total: 0
Jitter
Maximum: 14.3 %
Average: 11.39 %
Scanning statistics
Number of samples: 3343
Average scanning interval: 1.00 sec
Glitches removed: 0
Would it be wise to return these CMC disks? Or are they still useable.