Thanks Polly, We didn't use them at all that day but the conditions were perfect i.e. the snow wasn't frozen hard enough, for 99% of the route, to make the going slippy. I wouldn't be up there without them though as another day could be very different!
Absolutely, all it takes is the right (or rather wrong) wind and a drop of a couple of degrees to turn ideal walking conditions into a frozen neve nightmare. Different aspects can, and often do, have drastically varied conditions too. If you even think there might be snow up high, even if you can't see it, take your spikey stuff. Better to have and not need than to need and not have.
Ben (from this site) actually did a good little vlog (not blog) about forgetting his stuff in the car and getting into a perilous situation on the Mamores.