I have replaced my stealth heated grips x1 due to the chrome wearing out. I have never had an electrical failure in the heated grips and here's why:
When you install the grips;
1) throw the crappy instructions away.
2) run the hot wire, (red I think) and the switch wire, (orange) together and hook them to a relay.
3) buy an extra accessory switch to fit in the blank in the fairing switch housing.
4) Set the grips on 6 and turn them on and off with the switch.
It's the switch on the end of the left grip thats the problem, so just set it on 6 and cycle the grips with the acc switch.
You can adjust the temp with the factory rheostat from time to time if you wish but don't use it for on and off too often or it will fail.
Oh, I almost forgot, if you want grips that really get hot like they're supposed to, the more rubber and less chrome they have, the better they will work, so the best ones are the smooth plain rubber grips with the chrome band on the outboard ends.....but.........in time the top layer of rubber begins to wear and blister, but they still work great, at least that's been my experience with them. That particular set of grips was on my heritage classic and failed on HIGH, and yes it was in the summertime, so I just put an on and off switch with relay on them.