I asked a monastic recently about Nyungne in Sakya - whether there was a Nyungne sadhana specific to the Sakya tradition. They didn't know for sure. However they related a story about HE Deshung Rinpoche being asked to lead a Nyungne. He didn't want to as he was concerned about the participants not being able to complete the practice. His students continued and he relented. However in fact a person became faint during the practice and had to leave the retreat.
I don't know when this incident took place but it was sometime before 1987. My response to this was that we weren't living in the 60's, 70's, 80's or even 90's anymore. People are in varying places but Westerners are engaging in serious practice to the best of their ability.
While nyungne has been increasingly practiced in Kagyu and Nyingma centers, I have never seen nyungne offered in Sakya centers. Hopefully this will change in the near future.