I've not had the pleasure of using an ULA pack yet, but I've taken my 2012 gorilla on several short weekend trips, the longest a 4-day 50 mile hike that involved a lot of rock scrambling.
I have suffered for SO long with shoulder pads that destroy my collarbones...during my summer 8-day trip to the Wind Rivers my osprey exos actually gave me open sores :(
I bought a gorilla this year to try a semi-frameless pack and I never knew a pack could be soooo comfortable to wear! The hip belt is great and I do not even notice that I even have shoulder straps. I am athletically built, not skinny nor fat...5'7" and about 150 pounds...the medium/medium is ever so slightly too big, but I think that it works for me.
So a very enthusiastic thumbs up for the Gorilla from a chick.