In reply to planetmarshall:
The DAS is IMHO one of very few true belay jackets. For me that means that belay jackets must be able to improve your comfort and warmth for protracted periods of shit weather. I would also put ME Citadel in this category.
I would not class things like Montane Flux or Prism as belay jackets, they are glorified fleeces, not belay jackets.
You pay a price in weight and bulk with a DAS, but it won't leave you cooling down after an hour. Stuff like the Flux is a short fix - the heat will soon get out. I run warm, but in really crap weather, you want a big gun not a spud gun.
Outside are selling DASs for £150 at the moment.
You know it makes sense.
Post edited at 17:58