I have not had a failure yet and it seems that most of the failures I have heard about have been brought about by an install of different handlebars and/or internal wiring that was maybe not done carefully enough.
My buddy has an 09 SG and he said that he was feeling a weird idling when he was recently riding and when he got to a restaurant and then when he started it on the way home it wouldn't idle well or throttle up (eventually went into limp mode). He did make it home after a bit of time but when he took it to the shop they said he broke a small plastic piece in the grips. They replaced and he seems to be ok now. Cheap plastic is not the way to go in something that could leave you stranded. I don't think this was a good move by HD but we will see how things go.