Experimenting a bit with grain and thinking “well that’s an area where Lightroom still has an edge” (but honestly, I haven’t double checked and my memories may be a bit hazy; I should’ve made a comparison but tonight I’m lazy).
Then I’ve found this thread and wow this truly deserves an article of some sort and to be put on the front page of the NYT or something.
Anyway, I’ve understood perhaps 1% of all the math above, but what I did understand is the meaning of the midtone bias slider in the grain module. I think the effect is really good and realistic:
right: grain 1600ISO/strength 50% / midtone bias 100%, left with midtone bias 0%
Apart from the blog post or article mentioned above, I also think that the online manual should be updated because as of now, it does not mention what is the midtone bias slider.