To me, Ricoh DVD+R DL 2.4X are superior to Ritek's DVD+R DL 2.4X :
With 1620 B7W9 (the changelog adds Ricoh DL support) :
http://club.cdfreaks.com/showpost.php?p ... stcount=67
Another one with another 1620 B7W9 :
With the LG GSA-4163B, it's even better. I've seen some amazing scan on every brand of DL (Ricoh, Philips, MKM) but RitekD01 (just average...).
Note : The new BenQ 1640 has some problems with Ricoh DL at layer break, but it's a firmware issue, I think it will be solved in the next firmare. Look here :