Concerning the reliability of the sim versus real life.
UPRT certified simulators should have a dedicated page on the instructor station showing where exactly you were in terms of reliability of the model throughout the stall. It should show a line for Flight Test, for Windtunnel and for Engineering. In decreasing order of confidence.
Different envelopes for different configurations.
Another aspect to consider is the wings roll off model. Airbus adds a forced (randomized) wing roll off, left or right, during the dynamic part of stall entry.
I have been working on UPRT implementations throughout the industry and worked extensively with flight test teams from both OEM's. Feedback has been that the real interesting part of the stall recognition (not recovery) is the buffet threshold of perception and the deterrent buffet for a fully developed stall. Also, it was noted that wing roll off doesnt alway happen, hence it can be disabled from the instructor station usually. The deterrent buffet is so strong that you really dont want to be there in the first place.
Lastly, obviously, stalling in Alternate Law is quite different from stalling in Direct Law in that in Alternate you will be significantly out of trim through recovery. I always found stalling in Direct more manageable as you have full control over the trim. If I recall correct the Airbus procedure for stall entry is to reduce speed with around 1.5 kts/sec to VLS, maintaining 0 V/S using the THS. Then let go of the THS and apply backstick (gradually), still decelerating with 1.5 kts/sec, and encounter the buffet onset and slowly developing into a full buffet. Wings drop and recovery starts.
I had a discussion with an experienced instructor who said that stall training, especially in alternate, beyond the stall warning, is not positive training. Students should be taught to recover as soon as stall warning comes up. Even for stall training in direct law, he said, it should mainly serve as a method to recognize stalls (through the buffets) and a student should not "get used" to manually fly into a fully developed stall. As an alternative he proposed that the instructor flies into the stall and hands over controls once the stall is happening. This comes closer to startle / uprt training perhaps. Different topic.