In reply to EveningWind:
Well, I get that you want people to confirm your choice of the Mammut trousers (if that's what you want, they seem great), but there probably needs to be some clarity/distinction of different types of 'softshell' in the context of this conversation?
I've worn an old pair of Mountain Hardwear Schoeller trousers for exactly what you're talking about. They're not insulated in the way that, say, Vapour Rise is. I run very hot - as in it takes alot for me to even bother putting a jacket on - but haven't overheated in the trousers. I've worn them in the Alps in good and shitty weather and in Snowdonia in January. This has included (due to the really shitty weather in the Alps this year), after 5 hours or so on a ridge, spending half an hour practicing self-arrest and then walking back down to Cham in the rain. Not once did I think about needing waterproofs.
Each to thier own. But if you want to go 'fast and light' as you said, I'd seriously think about some of the truly light options or just not bothering and spending the money on a single pair of trousers that can hack it?