Greg,
I have a 2010 4 cylinder Outback. No problem pulling. Even able to pass other vehicles on a 3 mile climb up "Nodine Hill" along I-90. Also, I do not have trailer breaks either, not needed yet. Also have never pulled thru mountain passes yet.
I bought the Outback because Cary said it is the number one towing vehicle seen at CI while picking up tears. So if there are any issues, blame Cary.
Jenn's outback is a 6 cylinder. As far as I know she has not had any issues.
Craig has an older Subaru Outback that he uses. Craig's mouth piece will have to speak.
Jean