Jim-

Where is the house?

In my previous SoCal home both batroom fans had their flex aluminum
ducts terminate near / against the gable end attic vent

I never had any mositure problems but SoCal is near desert conditions.


If you're in an area where condensation could occur make sure you do it
right. You will be buying a lot more trouble downstream

The "correct way" is a roof penetration. The soffit solution is ok as
well, as long as the flow terminates with an acceptable "vent cover".

cheers
Bob