In reply to Carolyn:
OK, a few more questions.....what's the difference between the DAS and the micro puff? Can't find them both on the same site, even Patagonia's. Boxy is likely fine over layers, so will look out for bargains, cheers.
Toby, what's the pack size like? It doesn't necessarily need to hang off harness for rescue team stuff, it can clip onto whatever piece of kit's on my back or squish into some of them. Or be in small rucsac worn loose over rope bag, etc. More a case of often not taking a lot of personal kit, so needing options to carry it on something else.