Digging up an old thread. I decided to go this route; however I went a slightly different route. I discovered that Wilderness Specialties uses this molle IV frame on their Bighorn pack. I bought two frames on ebay for 10 bucks in new condition, and purchased the upgraded suspension from Wilderness Specialties along with their meat hauling sling. I then bought a Kuiu Icon 3200 bag and attached it to the frame. I'm still working on the bag attachment, but so far for what I have in it, I like it. Its surprisingly light.
The WPS frames look like some of the best budget haulers out there, how much did just the suspension cost you? I haven't used one yet but I have to assume their belt and harness is a huge step up from the military suspension.
I too love the infinite mounting options on the Down East frames, but haven't found a suspension I really like. I made a lumbar pad adapter and have a frame set up with Hill People Gear belt and shoulder harness, but it isn't perfect.