OK I will probably regret this but I have had two R1100S's. Last one was a boxer cup replika (trying to justify myself here!).
Anyway, being a BMW it came with heated grips. Being BMW it came with two settings, hot and meltingly hot.
However if I wore thicker gloves for the winter, it stopped the heat coming through. If I wore thinner gloves, my hands were nice and warm on the palms but cold on the back.
I settled for medium thickness gloves (Alpinestars gortex) on a hot setting and found them pretty good. BUT I agree, pointless if the rest of you is cold.
Having been used to them I would be lying if I said I hadnt considered them again, but I dont ride my Ducati enough in the winter to warrant it.
On prevous bikes when I was commuting all weathers I tried 'Oxford Muffs' and found them no good at all.
Heated grips work if you get decent ones, I have tried cheap ones and they dont work & look crap too. If you are going to get them, get the proper ones, even see if BMW fit them, and get a heated vest. That combination would see you through most things I would have thought.
Now I will await the onslaught of having been a BMW rider with heated grips. Bring it on!!!