Well I just received the new LG burner because my ASUS was acting up (not ejecting properly and other issues).
Also, I was NEVER able to burn dual layer Bluray discs with the ASUS even though it was supposed to. I tried everything, including REAL cdrecord (compiled myself), but the burn would always fail when switching layers.
Since the drive had an issue and I had to spend some $$$, it was time to try again with the new LG WH14NS40.
I first tried backing up my pictures (~40GB), with xfburn because I wanted to use libburn as the fork of the cdrecord apps are known to have issues. Not sure what the problem was but after spinning up a bunch of times it just crapped out with an unhelpful error.
Next I tried Brasero, which also failed miserably.
Finally I tried k3b which used mkisofs and it actually worked! Switched layers fine, finished, and verified. For posterity I specified a UDF based filesystem.
Googling I see so little useful information about burning dual layer Bluray discs on Linux I figured I'd mention it here for anyone else interested.
Thanks, Richard