Here's my opinion on the AGC vs. the KUIU now that I have them both...
AGC... It's beefier, I like the harness straps much better than the KUIU. I was concerned with the lid since I like to grab my binos often while I'm hiking around. The lid folds right inside with no problems which was great! Now I can fold the lid in while hiking around hunting and close it up if it starts to rain, snow or I'm on a 4 wheeler etc. I can crawl with no problem and not have my binos fall out with the lid open too. My Leica 1000R fits perfectly in the front pocket. I also carried 5 rounds of ammo in the side pocket, wind indicator in the other side pocket, and my license and ink pen in the back pocket. Dropping my pack for a stalk and having everything I need is great. Here's the only bad I found... It's definitely a little bulky but after I started hunting and not paying attention, I didn't even notice it. You get used to it really fast. I like to run the harness as high up on my chest as it will go. I noticed a couple times the straps loosened up a little bit and I had to retighten them. I think I can fix that with a small modification without any problems. The other thing is having the lid open all day, there was some debris (leaves, and such) in the bottom. It would probably depend on the terrain your hunting if this would be a problem or not. Really not a big deal, you just flip it upside down at the end of the day to empty anything out.
KUIU... It's definitely smaller, and more compact. Unfortunately that's the only area where it really shined. The harness straps are thin which makes it feel unstable. The fact that the harness doesn't hook to the pouch but instead to the binos itself is a major issue for me. It just doesn't feel right. I didn't find it one hand operational very easily as it's advertised. If I leave the lid open like I like to do and crawl around the binos fall out, which is a big problem. There's not much extra room to carry anything else. I really liked having my range finder in my bino harness.
Of course this is all personal opinion and everyone has a different one. There's probably not one that's better than the other. It just depends on what works for you. That being said the KUIU is packaged up for return! I'm really happy with my AGC!!!