You also might want to look at Blu Ray Media: TDK Review
http://blog.consumerpla.net/2011/02/blu-ray-media-tdk-disks-review.html where the comments are telling ...

... and the entire review starting at Blu Ray Media: Best BD-R Discs Review (yes, Verbatim is mentioned)
http://blog.consumerpla.net/2011/02/blu-ray-media-best-bd-r-discs-review.html

Dunedain said:

Burning at very slow speed ...

Too slow can be just as detrimental to "a good burn" as maximum speed:

MAM-A Archival Discs - FAQ
http://www.mam-a-store.com/faqs.html

"When duplicating an analog tape, recording at the lowest speed yields the highest quality recording. For optical discs (CD-R, DVD-R, Blu-ray), this is not true. As a rule of thumb, we find that the best recording is roughly at half the top rated speed."