here is a little video, showing all three packs in Eberlestocks "Just One" series of packs
Nice video showing the comparison, I have the G4 operator but its more of just a gear bag and will accept a larger tactical rifle and I'm planing on selling it and going with the J107 being its more versatile and can expand in cubic inches for back country Hunting.
There is a modification that I have seen that would make the load lifters functional. I haven't tried it yet but I will and post my results.
I have the J107 and really like most of the features. As far as fit & carrying capacity, it's great. I can carry a ton of stuff, but what I most like is the huge water bladder. If it's hot I can load it up with ice and have icewater for a whole day! What i don't like is that you have to remove your rifle before you remove the pack, but that's just being picky. I also would like to see the top part-the removable part you can convert to a fanny pack, done away with, but only because I hunt deer with a longbow and cat quiver. I wish Glen would do an accessory to carry a longbow or recurve in addition to that butt bucket for compounds.