Thanks to a recommendation from Chas0039 I ordered a Lite-on 169S a few days ago.
Ripping a dual layer gave me the following initial results:
Lite-on 169S 15 min 53 sec
Plextor 716A 11 min 04 sec
BenQ1620 16 min 31 sec
BenQ 1640 11 min 01 sec
then I downloaded http://codeguys.rpc1.org/firmwares.html
and set everything to max
Liteon 169S now ripped in 9 min 36 Sec
As another test I tried to get it to rip an old movie which no other writer could read. Basically it did the job with 26 errors and other the restored movie
was a little foggy towards the end it was no worse than many videos from the 1980's
I can't think of a reason wy any shouldn't have one of these - even if just for the occassional difficult disk. I had 2 and 3 year old data disks which are starting to fail and need to be reburned - the Liteon 169S way well save other disks.