eVent - which is the ePTFE fabric used on those jackets handles interior condensation poorly because is doesn't have a hydrophilic layer like Gore-tex does. Less layers increases breath-ability but if moisture and condensate build up you will need large pitzips and lots of airflow coming in to remove that condensation because the eVent can't remove it like the Gore-tex does.

I also would be interested to hear about long-term durability with the eVent and a backpack... all ears!