I agree with Jay about using handlebar mitts. Just about to refit mine on to the GS as the temperatures are dropping.
Was using them last January when it was around 4C and didn't even need the heated grips on, even with summer gloves.
Wind chill is a big factor.
Mine cost a tenner on eBay last year and worked fine. Might splash out for a pair of Tocanos this year, though.
Yes, they look a bit naff but makes all the difference to riding comfort in the winter.
Besides, you'll only meet other BMW's on the road from now on.