Thanks for the tips Steve.
Brad, it occassionally drops to around 0 deg C where I live on winter mornings. I've had the Oxford Hot Grips on a previous dual purpose bike and they pulled me out of early stages of hypothermia a couple of times on day long cold wet rides into forests. My reasons for fitting the grips is more of a comfort thing and you'd be surprised once you have them, how often you give them a bit of a run. They can turn an unpleasant ride into a more bearable ride at times especially when your bike is your daily rider.
Cheers
John Q