Same here. I am on set #4 in 4 years, 50 k, no rain.

 

Simon, my police motor unit had the HD heated grips installed in our fleet of 28 '08 FLHTP's. I can unequivocally state that the HD heated grips are overpriced, poor quality and perform maginally AT BEST.

Many of the grips on our police bikes failed entirely or functioned erractically. Some only provided a little heat, some had the entire grip slide off. Of course HD told us that, except for total failure, everything else was "within design parameters"-In other words go pound salt!
I'm looking into a set of Heat Demons for my Ultra. A lot less $$ than the HD grips, and a lot of HDF members seem to like them.

 

BTW-Heated grips work best at low temperatures when used in combination with Hippohands or a similar product that shields your hands from the wind. Our guys will ride with light gloves on in frigid conditions (when the damned HD grips are working properly, that is!).

Without the Hippohands even the best heat grips can't overcome wind blastand that includes fairing bikes. The Hippohands have the added benefit of keeping your hands dry.

 

Can the Heat Demons or other heat devices be used with internally wired handlebars?

 

Screw the overpriced HD grips -get a set of Symtec Grip heater kits/ mine cost $30 and work good. I commutted in any weather above 38 deg. and they did the job. IMHO good heated gloves are better but when ya get caught in the rain on a 75 deg day you'll be turning them on, espically if you have old tired hands like me. These are heat grids that glue under the hand grips. All switch and connectors are included.
I know murphkits.com has the best price usually

 

The problem with Hippo Hands or similar is you need dirt bike type hand guards installed first to hold them off the levers. Happy with my heated gloves, they heat the fingers and back of the hand, the parts that get cold. I also have heated grips, they're great at in between temps (above 50F) but not near as comfortable in colder temps as heated gloves

 

+1 on everything you said except, at my age my hands get cold very easily so I find the effectiveness of my heated grips to me minimal under about 40 degrees. I've had mine for 6 years and they continue to work well. After riding into Yellowstone last year at 29 degrees, I decided to invest in Gerbing heated gloves. Someone should design a glove with a conductor inside that will pick up the heat in the palm of your gloves and transmit it around the fingers.