A bit of a necro thread here but I'm going to add in my bit for anyone who is looking for a bergen in the future.
I had the same requirements as OP a few years ago, went looking for a new bergen and came across a Lowe Alpine Saracen 120l made under licence by Arwy in Belgium.
It's in m81 woodland, has a big panel of PALs webbing down the front and despite not being made be Lowe Alpine, the build quality is very good overall.
I can get all my kit into the main compartment, including my assault pack which is a massive Karrimor SF TECMAC 50, with room to spare in that compartment and the rocket pouches empty.
I have tabbed with it weighing almost 50Kgs and it was quite comfortable despite probably knocking 10 years of my knees.
It is not designed to be worn with armour which is fine as we don't normally wear CBA with a bergen.
My only 2 complaints are that the hip belt adjustment is a bit fiddly and cant be done while wearing it and the bugger weighs 4.5Kgs dry!
I would definitely recommend it unless you are wearing belt kit