After some more testing i came to conclusion you need SolidBurn ON and WOPC ON to be safe. In some cases you can disable WOPC but then you better enable SolidBurn or else you may get unreadable disc (pic above).
On the other hand, you can disable SolidBurn when WOPC is enabled. Results may be the same or similar if media is in firmware database. If not, its better to leave SolidBurn ON for unknown media. SolidBurn for known media may help when there are more than one production line and quality of the same brand.
OverSpeed also enables SolidBurn so i dont see any benefit enabling it for 16x media. Maybe it helps with old 4x media when there is hard limit to 4x speed in firmware, but then again SolidBurn will reduce speed, no matter if OverSpeed is enabled or not. In other words, pretty much useless feature for new media. May be useful for old.
So in conclusion - i observe nice improvement in quality on 16x media, only thing which i dont like is increased recording time. There are ways to speedup the process by disabling SolidBurn and WOPC but in most cases it is not recommended. After few more bad DVDs regular user will just leave all ON to be on the safe side.
QSuite 2.1 could be improved by checking all IDE devices at startup. If you have BENQ as a slave drive and some other as a master you will get unneeded ‘sorry BENQ drives only’ message since application checks only the first drive.