I think simulator manufacturers lack data outside the normal operational envelope of the aircraft. There is no guarantee the jet will behave in the same manner that the sim, when ie. upside down og knife-edge. I´ve flown both 737 and 757 sims inverted without problems but I have no doubt the actual experience would differ somewhat. I however think some practice in the sim could not hurt in any way, but beware the inaccurate data.