Pete, known of us know that yet. All I know is that they work great on low, with thin gloves, in 35-40 degree weather. I believe the company is from Minnesota and originally made them for snowmobiles. Never had the MOCO heated grips to compare to. Maybe Terry could say how the HD's compare to the MOCO's?
Unfortunately, we now need heated clutch/brake levers as they are pretty cold when going from the stock grips.
Well, I never ride without some kind of full fingered glove on, so I generally have mine on either 2, 3, or 4, depending. On the HD grips, I usually had them nearly to the max or maxed out. The Demons are warmer, IMO. If I have my regular deerskin gloves on, I can get by with setting 2, but if I've got the PCI gloves on, I generally need them on 3 or 4. Because I'm never without gloves, I don't notice the temp of the levers, plus I ride 80% of the time with two fingers covering the levers. It's a habit I got into many years ago and the way I'm most comfortable.....I know the courses you take say not to do that any more, but I think that is because new riders don't need to be grabbing a handful of front brake when they aren't used to it. Plus, I have just never cared much for the lever covers, no matter the style...I likes 'um shiney...

At any rate, the grips work extremely well, IMO, and like Bob said, they were probably made for snowmobiles, so I suspect they will hold up well. Hell, only the MOCO seems unable to make a heated grip that is dependable...go figure.