In reply to bivy spirit:
Ok, i know i'm gonna end up writing a bloody book or something about this kind of shite anyway, so i might as well start now!....
...i couldn't justify the cost of a reactor either, until, to give one example, i realised it could let me totally re-think what i could be 'capable' of in a terms of approaching 'extreme alpinism' a-la monsieur Twight, with a lot of careful thought and planning (and co-joining with other incomplete skills and theories learnt over the years).
So....to give away one aspect of it:
go away and consider the middle-high alpine environment with its typical availability of liquid water, but unlimited availability of 'non-liquid/useless' water. then imagine a very full-day route, for which failure equals 2-3 days before safe return.
then calculate the cost/weight of a jetboil + its canister + its weight + its volume + its efficiency and incredible increase in time saved in the whole process of refueling humans(with both H2O and food energy).
Then do exactly the same/all the above with an MSR Reactor
Then do exactly the same/all the above with an approach which refuses a stove, and measure the 'safe compromise' volume of water to take (for arguements sake lets say we can agree its is likely to measure a minimum of 2-3L, PER person). now measure in your mind the volume that those 6 litres take up between a pair + their weight (think about it, its precisely 6kg)
Then? compare and contrast.
I'm aware that the first thing you are going to come back to me and say "are you crazy!? i only want to go bivying in my back yard, how did you manage to turn this conversation into a crazy ramble about all that shite you've just spewed up there"
Well...i'm also aware the above may sound a bit extreme, crazy even, and blur the line between metaphysic,philosphy and climbing! but hey, how'd you know that that secretly is all that is the difference between you, I, the mere climbing man, and the 'super'man climber!? and in every area of human endevour including climbing for that matter. (nietzsche's "Übermensch" btw, case you were wondering why the hell those last 2 sentences sounded extra odd)