This is some research from the ATSB site regarding the PA31, it is a list of accidents/incidents involving the aircraft for the last 30 years or so. I have not included the latest accident as there is not enough evidence available yet. Also not included are a number of landing gear related accidents.
VH-OPC Most probably loss of control due spatial disorientation (no mechanical defects found)
VH-ZGZ Most probably loss of control due spatial disorientation (no mechanical defects found)
VH-LHR Fuel Starvation
VH-BTD Loss of control, spatial disorientation (recovered and landed)
VH-WAL Precautionary landing due to low fuel
VH-TFX In-flight shut down landed on water (investigation still in progress)
VH-ZMK Failure on approach and landed on taxyway
VH-PYN Broke up in thunderstroms
VH-OAO CFIT/Disorientation/Ice (no mechanical defects found)
VH-MZV Double engine failure induced by pilot (mixture control)
VH-IGW In-flight shut down with successful landing
VH-PRJ Take-off with control lock installed
VH-BSM In-flight shut down, could not maintain altitude due flap extension and also instrumentation issues
VH-OCF In-flight fire and shut down with successful landing
VH-UBC Double engine failure induced by pilot (tank selection)
VH-MZK Double engine failure (whyalla)
VH-JCH In-flight shut down with successful landing
VH-TTX In-flight shut down with successful landing
VH-LTW In-flight shut down with successful landing
VH-FML In-flight shut down with successful landing
VH-FMU Fuel starvation
VH-NPA In-flight shut down with successful landing
VH-KIJ CFIT whilst circling
VH-WGI CFIT whilst circling
VH-UFO Double engine failure induced by pilot (tank selection)
VH-NDU CFIT whilst circling
In bold are the aircraft specific occurances with the shut downs from MZK to FML all during the time the crankshafts were suspect.
All the aircraft related failures (Except MZK) resulted in the pilot and passengers walking away. I would not say that the aircraft is dangerous or even marginal, considering the types of operations these aircraft continue to be used you would think the rate would have been higher.