It sounds like you may be experiencing more flicking than is typical though. I would contact Samsung as it is possible they have a way to fix the issue. Unfortunately, because Freesync is built off an open standard, AMD doesn't have any control over the panels and scalars used. They should probably get a little stingier on minimum performance needed for Freesync certification.
I do use Freesync on my Acer 27", 40-144Hz at 1440p, and I don't see any of the flickering issues. That model uses and IPS panel however, which seem to perform better in regards to the issue. The problem is panel dependant however, with TN panels being the most problematic.