I don't see anything wrong with training in the aircraft, surely it must be safer doing it in an emb than a chieftain?
Not at all, whilst the chieftain may have less climb performance on one engine it is a much less complicated aircraft. An engine failure in a turbo-prop at low speed can require more effort to retain control than the lower powered pistons like PA31 and C400 series. An autofeather failure at low speed and altitude and you might be in trouble. There are many scenarios which could occur during and shortly after take-off which could lead to loss of control. Unfortunately all of them are a result of someone making an error at some stage whether its pilots, engineers, a part manufacturer etc...
The simulator if used correctly will prove how critical some of these failures can be and is invaluable in training crews.