Surprised nobody else answered you however simulations especially switching depend on how well you simulate all the other circuit elements, especially the driver, the load if its inductive, any current the diode is going to handle and any potential avalanche power. I have done plenty of sims and actuals with mosfets, less so with igbt's and I would not say the sims have been an order of magnitude out but as I say it depends how much effort you put into modelling. Tuning at the prototype is fairly easy unless you make a bad mistake (heatsink to small, bad layout resulting in excessive ringing etc).