Whilst teaching aeros in a 'Dog some years ago and heading upwards for a stude stall turn right there was a strangled "I'm going to die" noise from my left (I was watching the right wingtip). When I turned to look at the poor stude he was holding the grip, which had "come off in his hand, guv" and which now had a couple of wires sticking-out of it - but not as far as his eyes were sticking-out of his head ;-) I laughed and asked him what he was going to do, whereupon he applied rudder and sorted it out. RTB and landing were flown by him using the stbd stick - a useful but unplanned exercise. Moral of the story: the grips can fail.
I can't recall where it broke, but there was a small amount still attached to the column.
HFD