I have had a few rides now in Sim mode that have not dropped out so I am happy with how it feels in the game.
Although, I think you may be a little light on with the resistance when the grade is 9% and up. There is now way I can be normally in the third last cog on the cassette outdoors at 9%.
Loving the feel of the kickr in sim mode on the island. It’s close to real for mine.