I have been running with OEM grips for 3+ years now without issue. They get hot enough, when cranked all the way up, I need gloves to to hold the grips (I wear gloves anyways...but you get the point). That said, when I first installed them I had two pair fail two weeks apart; the cable end tore out of the grip housing. What was in common with both failures is I had gone past full throttle (totally cranked) and ultimately changed the direction of force on the grip where the cable attaches at the end. Honestly, that's never necessary (for me at least) and I was just exploring my new beast. I haven't had a need to crank that hard since and I've had no issues with the grips...but I do keep the original throttle grip in my pannier just in case.
-MIG