I have been using only DVD-R with the LG so far and can only say, it is okay, maybe even good. No problems, no damages discs, and they do work well on my laptops old Toshiba SD-C2402 drive. So nothing to worry about. BTW I use Verbatim DVD-R 8x (MCC 02RG20) right atm and no problems with them, especially if compared to the Samsung TS-H552B which only produced crappy burns.
I own an BenQ DW1620 since yesterday, too, and they are great together. The LG for DVD-RAM (unique I think) and the BenQ for testing, and both for fast and quite good writing quality. IIRC a NEC 3500 would be a little bit better than the LG if you dont need DVD-RAM, not sure about the 3520. I like both the BenQ and the LG, but heard good things about NEC 3500 as well.
Never tried +R DL btw, so cannot tell you anything about that ...