this thread is getting very medical orientated which is so outside my knowledge zone so i'll stick to the kit, the nato mug/bottle is fat as you mention, i was after a slimmer alternative myslef to have a play with and spent a day going round all the camping shops in cambridge, which to my girlfriends annoyance has plenty, and spent the entire day looking like a very confused kit perv trying to fit nalgene type bottles into mugs to see if there was a civvy alternative. i think i found blacks had a 1 litre nalgene copy that fit into their titanium mug which wasn't over priced. the whole thing seemed nice and light and very user friendly. the thing that stopped me buying was the capacity of the mug and its shape didn't lend itself to MOD boil in the bags which i use a lot. so i refrained which annoyed the gf even more as i ended up buying nout but filled numerous rucksacks with dumbell weights, ponced about and kit porned the flask section. lol it's all good fun!