well i'll never be again able to do test with the dvr-109, i exchanged it for a nec 3520a.
Not the best writer it seems, but at least compatible with ps2, xbox and without strange behavior, and cheaper. I wanted a benQ but it seems there is a pb with ps2 backup & dvd-r (and my ps2 do not like dvd+r, neither the xbox.
But thank you for the forums and everybody, it's an endless source of information.
Hope the next pioneer will be compatible with everything, working well, +bitsetting and allow overspeed burn (since pioneer never seems to acknowledge ritek x8 or x16 as x8 or x16, but only x4 - i'm fed up with this policy of recknognising only specific dvd's. Until that i'll never buy i pioneer again. (i was happy with my 105 only because of the modified firmware)