If possible try and get NEC instead than DVR-109. The 108 was oki as far as I can tell from the stories here in the forum.
The DVR-109 seemd to have been rushed to the market, it suffers heavy from firmware problems and other things as well. Min for example was DOA And I have read a lot about the 109 in here.
Its better to wait for the DVR-110 (if that is what it's going to be called, donno). But for now, get another 108 if you must have pioneer or go for a NEC (3520 or 3540). They seem verry good what I can tell in the forums, they had problems with the early models.
My first drive was a pioneer dvr-106 works like a dream, its just great but now that 4x media is fased out and 8x and 16x is produced I need a new burner.
You can't (should not) but 8x or 16x media on a 4x burner or older, since it uses a different technic to burn the discs. And besides I want a better burner, newer technology etc
If you get a DVR-109 with firmware 1.40 then I think its oki but still a bad drive from pioneer (106,107 was way better) not so many firmware problems and other issues.