I've had both.
On my Sprint, I rode solely with the Gerbing heated gloves and they worked great until I got to 10F and below. At those temps, the tips of my fingers typically got numb by the time I got to work (about 40 min. ride on busy mornings).
Since I got the new Connie, it came standard with the heated grips. I can't believe them. They are awesome. I've ridden to work down to 9F and my hands have not gotten numb. They were cold but not terribly so. If I had the deflectors, they'd have been toasty warm.
Keep in mind the size of the gloves you buy. Don't get them too tight. A little bit of wiggle room allows the heat to flow around the fingers and keep them warm all around. I have the Tourmaster Winter Elite gloves (have had them for several years).
Of course, both would be ideal. I haven't installed an outlet for the Gerbings yet. That's gonna be sweet for the really cold days....
Just my .02.