Just got an AMR, have put about 18 miles on it. I'm liking it a lot. I can't imagine not having access only through the top. It compresses pretty well, but it's still big. However, on my budget, I had to choose one, so I went with it because it's large enough for anything I could ever want, but compressible. I bought two spotting scope pouches to go on the outside, and one thing to keep in mind when the pack is compressed is that there's no webbing matrix available to attach those pockets. Well, it's there, but it's all convoluted and they don't fit nicely on the sides of the pack as I thought they would. They'll work well when it's full though. I have a guide lid, which is great, and two large belt pouches, which are awesome for small items you want close at hand all the time: GPS, point and shoot camera, extra shells, etc. It think the belt pouches are essential because the belt is wide enough on the duplex frame that it pretty effectively seals your pants pockets, so no quick draw there.
The bottom of the two integral pockets is the most accessible, requiring no straps to be unbuckled to gain access. The top integral pocket is mostly covered by the lid.
It's definitely more fiddly to get into the main compartment with the pack compressed. The zip to access the bottom of the bag doesn't slide as easily as it would if it was expanded (like sliding the zipper slider over a roller-coaster). The guide lid slides down too far, exposing the draw cord closure of the top of the bag if you're not careful. Even with the top/front/hinge lid straps tightened all the way (maybe I'm doing something wrong there, but it's not too complicated). However, I don't think these problems are avoidable on any pack that's not loaded out to at least half its volume capacity. I am impressed with how much you can control the vertical placement of items in the main compartment of the pack by trapping them between compression straps.
I don't have any experience with the other models, and have limited experience with this one, but these are my initial impressions.
Someday I'd love to buy or make a smaller daypack size bag or get a Tarryall, but for now, I'm happy with the AMR and will continue to tweak loading it compressed to maximize ease of access to my most frequently-used gear on day trips.