I have 3 Eberlestock packs and have owned several more (Gunslinger 2, X3, X4, Warhammer, G4, Phantom, G1, Halftrack)
I like them, but you have to understand them fully before you purchase. The scabbard is awesome, but it also puts the load away from your body and shouldnt be used for long movements without a weapon inside. You can tighten it down semi-flush, but it still is different than just having the main compartment up against your back. The main compartments are almost all the same, the packs are built around a common base. That main compartment is pretty small and fairly narrow, the majority of the differences in packs is the external pockets they have.
If you are carrying a weapon, their scabbard packs are awesome. If not, go with something else.
If you have a large load, use a larger more open pack. the Eberlestocks are more compartmentalized and are hard to carry larger items in, like armor and helmets. They just dont have that large 3500ci open bay like an ALICE does.
With the said they are extremely well built and thought out and are very comfortable. You just have to know what you want it for.