I burn them at 8x and 12x for Verbatim DVD-R rated for 16X. They burn with very high quality scores in my Benq DW1640 like all other Verbatims do.
As for the newest firmware rule of some suggested, it's not always the case to have the newest firmware. Which was why I'm inquiring on the difference between the two. For example, the Benq DW1640, many would agree that the BSLB (which is somewhere in the middle of all the firmwares available, and definitely not the newest, over a year and a half old actually) is the overall best firmware to have with the best balance of quality and other benefits.
I doubt Pioneer keeps up with firmware updates as frequently though. On the other hand, I would think most dvd drives should have no problem burning a quality brand such as Verbatim. Their media tables are usually highly optimized for the high grade medias like Verbatim and TY.