Thanks, I tested different grain patterns from Cinegrain but I decided to go with their Kodak 5217. I think the problem is that I shouldn't have uploaded this version to Vimeo. I'm not very technical but I read somewhere (maybe from you) that the compression they use in sites like Youtube and Vimeo doesn't work well with grain (and noise).
This version was for festivals only (withoutabox screener, etc) which in the end turned out to be a major disappointment :-)
But we had a screening of this film in a local theater a few months ago (2K projection, DCP) and the owner of the place let me watch it two days before (so in case of any problem, I could make last minute adjustments). I was a bit worried about how the grain would look on the big screen and even considered changing it to a finer grain pattern but at least to my eyes, it looked great, less "distracting" than in this version you saw on Vimeo so I decided not to change anything.
I didn't noticed anything with the highlights though but now that you mentioned it, I'll take a closer look. Thanks again!