No offense man, but why would I RMA it?  It's working as advertised, and actually, even better than that since I'm burning 4X media @ 8X.  I tried the DVD's I have made with +R discs on my two set top DVD players, on my neighbors DVD player, and a friends DVD player, and the discs work in all of them.  I burn 4GB in under 7minutes, which is quite fast IMO, and if the drive does have issues with DVD -R, I have no plans to ever use that media anyhow, so it's irrelevant to me.  Also, the NEC may be dual layer, but I think I'll wait to go with a Dual Layer drive until they are more mainstream, and the media is cheap and readily available.  I generally never buy the first generation of any hardware, because you usually end up kicking yourself down the line when faster and newer drives are cheaper.  
As for Nero, I wonder if you read about the issues with earlier versions of Nero's causing problems on certain DVD burners.  I came across this in my research, so I made sure I had the lastest version of Nero 6 Ultra,  and I have had 0 issues other than the first bad write with the old B370 firmware.  Also, my buffer never drops below 95%, so it sounds like to me, you might have just gotten a bad unit. You do realize that your experience with one drive has no statistical relevance to how reliable these drives are right?  It's the same with mine.  Just because my one drive is operating flawlessly does not mean all of them will.  
Anyway, I'm glad you are happy with your NEC, and I'm happy with my Nu-Tech, so I don't see the problem.
 
Edit: Also, you do realize the the -R/RW format has no dual layer media format even announced yet, and as of now, the only dual layer media that will be available is +R/RW.  IMO, -R is on the way out...maybe not right away, but down the line, I think +R/RW is plainly the better format.  Here is a good article @ CDFreaks.com regarding the two formats.
Why DVD+R(W) is superior to DVD-R(W) - @ CDFreaks