I have them on my Tiger. Believe it or not it does get cold here in the panhandle of Florida (Fort Walton Beach/Pensacola area). Cold meaning it gets in the low 20s on occasion. I was riding on the interstate one morning when it was around 30 degrees and my hands were freezing. The whole time I was riding I was thinking about my bike being prewired for heated grips and also that handguards were an accessory option. Well, long story short I had handguards on the bike within the next couple of weeks. The reason I'm posting is to let you know my thoughts on them. I think they help a little, but nearly as much as I had hoped. My hands still get cold with them. I think the air flows over the top and right onto my knuckles. I'm thinking I may go ahead and get heated grips and between the two, hopefully, my hands will stay warm. Another thought I've had, however, is to simply get some heated gloves. I'd love to find some reasonably priced gloves that operate on battery (no need for wires plugged into the bike).
Anyway, just thought I'd share my experience for your consideration.