As reported by some users, MadDog firmwares 2.Fx cannot change booktype for DVD+RW discs that were already used/formatted with the original DVD+RW booktype.
On my NEC 2510 with MadDog8X 2.F7 firmware, I have the same problem : I cannot change booktype for old DVD+RW disc.
To solve this issue :
1- buy new DVD+RW discs (!)
2- change the booktype on another DVD burner (a liteon one for instance) (!)
or if you have a NEC 25x0 burner, sorry for NEC 3500 owners
3- install an old HP firmware that can do that correctly from the tdb.rpc1.org page or maybe “old” 2500 herrie beta firmware based on HP fw with SL bitsetting ! beware : only for 25x0 owners !
Moreover, with the new Nero CD/DVD Speed 3.50, I was able to change the booktype of my DVD+RW without erasing it (but the disc was empty), using a HP520n 2.21 fw !
And then, you can reinstall new firmware for the newest strategies (and check new bitsetting default)…