Well, I certainly respect others opinions, but I would like to offer a different perspective.
My Ultra Limited came with the factory heated grips when new and I've been very happy with them. I've had no reliability issues or accidental on issues. The have six different heat setting and I've never needed more than the first three.
I've been riding in pretty much lower to mid 40's weather lately. I do not like the bulk of lined gloves or electric gloves tethered to a plug in. With the heated grips I use the same high quality unlined leather gloves I've had for over 20 years.
My caveat is my Ultra has some wind protection from the Batwing and hard lowers. Your results may very well differ on a more open setup.
Also, this setup is on the throttle by wire model set up, so there has to be instructions somewhere.