thought i might update this a bit based on stuff i've acquired and tried over the last few months.
the British Bowman and Mortar bags previously discussed turned out fairly well: good, solid kit that can be had for excellent prices. big advantages of these bags is the superb shoulder straps and hip belt they come with, and the fact that they accept the British bergen rocket pockets. slight downside (for me at least) was the fact that they have somewhat limited PALS/MOLLE panels. otherwise very nice gear.
next was a British Field Pack (when it comes in Desert DPM). same size and construction as the Bowman and Mortar packs __without__ the separate compartment for carrying those specialized loads. also comes __without__ a hip/waist belt or the means to attach one (without some inventive bodging). guessing around a kilo lighter than the Bowman/Mortar bag when empty. big bonus (for me) is a full PALS/MOLLE panels on the face and 1/2 panels on the sides, and the fact that as with the Bowman/Mortar the rocket pockets are fully usable. damn good bag IMO and it's quickly become one of my favourites. fwiw this bag is called Infantry Pack when it comes in MTP, otherwise it is exactly the same as the Field Pack.
finally i manged to get my hands on a US surplus bag, the MOLLE 2 Rucksack. it's a large external frame pack, far beyond the basic 40-60L range that kicked this all off but i have to say, i love this rucksack! mine came in the usual American ACU camo which is hideous and ended up in the dye bath at the earliest opportunity. the dye job was not an unqualified success -- mine is now what might be kindly referred to as "eggplant camo" -- but i don't particularly care.
the shoulder straps and waist belt on the MOLLE 2 are justifiably famous and are often bodged on to an ALICE frame to make the "Wildcat ALICE". the bag itself is very well made, has a strong zipped divider between the main bag and the bottom sleep compartment which is accessible from the outside via a cresent-shaped zipper. 1/2 panel PALS/MOLLE on the face and sides are totally servicable and there are 7 compression straps scattered across the bag in useful places. overall the thing is very comfortable -- it __is__ adjustable enough to accommodate a 1/2 stack gentleman like myself -- and is rated to carry 100 kilos if you wanted to punish yourself in that particular way. the only built-in pocket is a large meshed map pocket on the underside of the large lid flap.
all in all the MOLLE 2 is easily my favourite pack these days. i've added my preferred MOLLE pouches and have been carrying around a 20-ish kilo load -- plus the 4-ish kilos of the rucksack itself -- and am repeatedly surprised how comfortable the whole business is. it's not perfect of course -- it is NOT a small bag, it rides wide and low, and would not be a great choice for serious bushwacking -- but for me, for now, it's as close as i've come.
and no, that ain't me modelling the pack.