Hi Patrick,
I will have to be honest and say I have never tried Duralites. My warning is aimed more at preventing unautorized mods to the system. There is in fact no harm in using Li-Ions as such but based on data at my disposal at the time the state of the art was still in favour of Nicads in terms of current versus voltage. If the KS system is not happy with the battery supply it will respond appropriately. We get up to 10 starts from a 1700 Sanyo pack with a KS and Nicads are low risk in terms of charging. Hence I still use them...
Hope this clears it up for you. I would be glad to get feedback on the use of the new generation Li Ion packs in autostart apps.
Cheers
Andre
MD BMT