Yes, I meant +R and +RW, sorry for that. I indeed noticed that Nero won't burn 'em as -rom either, even as I specify this at the recorder settings dialogue box. The odd thing is that in it's log Nero does mention setting the booktype to -rom, but when I check afterwards it's still +RW.
Also, when I try to change booktype settings using CDspeed for this drive, all possibilities are greyed out...