Hi 
SO my old heavy trustworthy backpack I am upgrading now didn’t have any hip belt pockets and I have to say I was excited with the idea of finally getting a bag with hip belt pockets. Done are the days of trying to find ways of strapping and connecting my phone pouch and small 35mm camera 
So hip belt pockets is a tick for me! The Eyja looks great though! And again, Osprey as a brand seem to be solid and everyone who has one seem to be happy.
I have never actually seen a Gregory pack up close so if I go with that model then I am definitely taking a chance.
Volume wise I am looking for 60 - 65l range since this bag will mostly be used for 2 - 6 day trips with lightweight tent included.
I will go read up a bit about the hip-belt issues, see if I find anything. Thanks for the note one that!