I also really like the J34. What most people don't like on the Eberlestock packs is that they don't have great load lifters like some of the other designs without a scabbard. Having the rifle next to your back means everything else has to be further back than it would be on other designs. Also due to the scabbard the Eberle's expand out instead of up which can make them less comfortable and stable with a big load. The fact that they make an excellent daypack once you get to your hunting spot is the biggest advantage for me. It depends on whay you are looking for and how you intend to use it I guess. I've had up to 70lbs in my J34 and it packed pretty comfortable. That said if I'm packing an elk I'd grab the pack frame for the second load. I love the lay-out to, easy to reach optics and other items fairly quick. I have 5 eberlestock packs for myself and my fiance. Our 72hr kits stay in two of them and the others get used for hunting. Anyway, here are my thoughts on the ones I have
J34 - my favorite. I really like the ability to compress the scabbard and keep it quiet, layout is great. Downside is the 7lb weight.
X3 Lo Drag - To keep the scabbard quiet I have to hook the side buckles. Unless you have a rifle large enough to need it I'd avoid the military wide scabbard. The nylon material is also much louder when hunting than the camo models. If it was made in camo with a narrow scabbard I'd love it. The uplifting compression straps are nice and it carries 35lbs real comfortable and stable.
X1A1, also had an X1E - Nice packs but I like the long separate pockets of the J34 better. I prefer the J34's layout for an extra pound and a half.
Gunrunner - This pack is nice and light, thought I would love it. It has a loud lining on the scabbard and no way to compress it. When I pull my rifle out the extra room in the scabbard allows the pack to swing side to side and make the insides of the scabbard rub together, it can be loud. My fiance likes this pack so I had the local saddle shop add a couple compression straps to silence it and she uses it now.
Mini-me. This is a slick little pack when you are going on real short trips like stalking from a vehicle and only need a minimal emergency kit and water. When you add the scabbard you can't fit much else but it is real light and comfortable. The scabbard is quiet to. If you need extra clothes or a place to stuff layers you remove this isn't the pack.