Heated grips are one of the great inventions. I routinely turn them on in the summer on cool mornings and used them on the way back from the Vt. rally in the rain. Almost as good as wearing a hat
A couple of falls ago I bought 4 sets of bar warmers from a snowmobile supply place,paid $20 bucks for the 4 pair. They work every bit as good as BMW'S overly inflated price,and cheap enough that I gave away 3 sets for christmas presents
I run both. I have a 02 KRS with factory heated grips, I use these on cold mornings and in the rain during the summer. I have a Gerbing jacket liner and leather gloves for the colder times. During the winter(in WI), I usually run with the full heat on in the clothes and have the grips on high as well. Rarely do I get cold.