That's as may be, SASless... but I don't think you'll ever get into that one.
Helly-Hansen has been developing all-in-one suits for rig workers which will be used in the North Sea, not only for helicopter transport, but also for working on the rig. If I remember rightly, they use a latent heat principle with small paraffin capsules throughout the suit. I don't remember too many of the details, but essentially they're less likely to cause heat stress to the wearer in benign conditions and work well and are tough in the working environment and a survival situation.
Outsider_May09