My Lavro has seen at least a 100 trips down the solduc. Not a big deal, as a matter of fact the "sliding off the rocks thingy" has saved my arse on the duc a number of times, I don't know what I would have done in a aluminum boat in that situation. I would say that the fiberglass is a little more forgiving when you make a mistake and end up on a rock.
Mine was built in 1978, still going strong.