I had a bad 1620 last year, and I've seen posts with similar problems last month. Therefore, I cannot recommend this drive. Based on reviews in this forum, the NEC can burn lower quality DVD media (+R and -R) BETTER than the BenQ.
The bitsetting argument is weak, because modded firmware with bitsetting and riplock disabled is 100% safe and a snap to install with the NEC. One can even backup the original FW for future restoration. Don't BenQ owners have to disable riplock for DL DVD media?
Soon, all NEC 35XX drives will be able to test for burn quality. The NEC is also one of the quickest SL DVD ripper (max 16X). It may not be the best reader of bad media, but I have yet to come across a DVD that I cannot clean/repair to achieve a successful rip.