>Is Mammut Trion a good choice? it is not a great deal havier then the "small" companies , around 1600g.
The good choice is a pack that will be durable, carry the equipment and food you need for the trip, and do so in a comfortable manner. Period.
Admittedly, I've succumbed to the "cool" factor with a few pieces of gear, but after using them, I quickly realized that the coolness wasn't worth it. I had tried a UL frameless pack once, but now I use an Osprey pack because it does exactly what I need it to in a comfortable way.
If people are honestly comfortable carrying 25lbs in a frameless pack, then more power to 'em, but I'd rather use a little heavier pack with a light frame.