CS, our 420S jumped timing and bent valves without any warning on a cold startup (probably had experienced some backward rotation upon shutdown the night before causing the chain to loosen up on the sprockets since the tensioner is on the other side of the engine). If the car is in good shape and you plan to maintain it, then by all means get the chain taken care of soon. Find someone that knows how, has done several and will explain to you the procedure they use.