for the 3500 2.f8 has support for +RW bitsetting using the new WinBtype.exe utility, bitsetting through DVDInfoPro doesn’t work with their firmwares. Check out http://www.mdmm.com/drivers
or alternately TDB have a riplock removed and RPC1 version of the firmware. Note it will only work on +RW discs that haven’t already been burned with a +RW booktype (i.e. New)
2510a, I have heard Mad Dog is still waiting on NEC for Ritek DL support (it is my understanding this is Mad Dog’s top priority for this drive) and then RW bitsetting (not as many of their customers are requesting this.) Maybe they’ll get them in the same firmware. It really is up to the NEC engineers.