In reply to Robin UK:
I use the smock, for winter, scrambling, multi pitch days and skiing, side vents work well enough, also as stated chest vent aswell,
once its on, it's on.
have used similar to the jacket,
jacket is more suited if you intend to be removing it, and putting it back on a couple of times
Smock is on all day, the only real down side of smock for me is wearing pants with braces at the same time. as you have to either take your smock off to go for a dump, or wear the smock tucked into your pants which i find uncomfortable. and makes you look like your mum dressed you