>>Your hands aren't usually on the levers long enough to make a big difference.<<
Hmmm, that hasn't been my experience. I can feel the cold traveling from the levers to my fingers (or, more accurately, the heat dissipating from my fingers through the levers/heatsinks). After riding around for a few hours in 30-degree weather last weekend, my fingers were getting pretty numb from all the clutching and braking. I have motorcycle mitts which break the wind and keep my hands overall fairly warm.
After that day's ride the worst victims were my fingers and my toes, especially the big toes. They were quite refrigerated. I had to take a warm shower to water-heat them back up.
>>I use Dual-Star's grip heaters.<<
I've considerd using either heated grips or gloves, but I'm already using a Widder vest and I'm not sure the bike can handle the two, even though the Widder isn't set to it's full 35-watt heating capacity (yet). I did have my rectifier replaced with a unit designed for a Yamaha, which puts out .6 volts extra, so I may be OK on this.
I also just read about Heat Factory chemical heat pads and was wondering if anyone's ever used them. They have toe warmers that I'm particularly interested in. I'm wondering if I can wrap their larger pads around the hand grips and levers Perhaps just throwing a pair into my bike mitts might do the trick. Anyone ever use these?
http://www.heatfactory.com/