In reply to Brian Pollock: I like softshell garments, current one is an Arcteryx Gamma hoody. I only carry a very lightweight hardshell and have done so for many years. A Marmot Micra I think it's called and I've been tempted to leave that behind many times but it's so light that it hardly matters. Having said that I only go out when the forecast is good so walking up to a hut in pouring rain on the strength of a good forecast would be problematical so in a case like that I would probably take my Precipe jacket which is a little more robust but by no means a heavy weight.
In reply to Brian Pollock: I suspect if you end up doing any real.climbing in your light shell. It won't survive the experience. No problem if you have confidence in your decision making! For short routes take the light one
In reply to Brian Pollock:
Ultralight is the way to go. In the Alps you climb in good weather and hardshells are very much back up gear. If you are having to climb in your hardshell in the Alps then it's probably not its longevity you will be worried about!
In reply to Brian Pollock: most likely use for you will coming down.from a.hut in an afternoon storm, when it will be ideal. If your chimneying disintegrating choss when the storm a few holes in your jacket can be considered well earnt! I take it your flying and can't fit both in 20 kg.