First, none of the tests you are running measure the quality of the burn. You are mesuring the ability of THIS drve to read a particular media. Second, MCC is not crappy media. The mcc 02rg20 code you are using is probably the CMC made MCC and it burns very well on NEC. It tends to have a bit of a rise at the end or at the beginning of the burn but the total is well below 50 PI and it is not a bad burn at all. Third, I would expect to see exactly the scans you are seeing above. NEC does not make the best readers. Their 35xx burners, unfortunately, read very fast with burned SL media. When you put these two things together you get the problems you have seen above. Some TY is more redable at the edge, but not always. I can read the same discs you have above on my LG with a straight line. I get the same drops when I read the disc on my NEC. Neither necessarily tells me anything about how good the media is, how good the burn is, or how well the disc will play on a particular DVD player. Players read no where near 16X.
If you stick with the media in my sig, (some G05 is lower quality) you should have no problems with you NEC. Be happy. If you really want to see burn quality you will need to get a drive that supports quality scanning. NEC will add this to their firmware soon.
Here is a link to a quality scan for MCC 02RG20. It is from my LG but it is not that different from what I get on my NEC. Far from crappy.