I reckon the pros will actually be able to tell the difference.
We spent a long time back in the day arguing over 60hz vs 120hz and people throwing in the silly eyes can only see 30fps argument etc.
120hz is such a normality these days even the mainstream user has adapted to the higher refresh and can tell the difference. Personally I struggle with 200hz and 144hz, although im sure some can "feel" it is different.
I do like the idea of a blind test with this. Thing is though, a fair unbiased test might be tricky as there are so many variables that can affect it. FPS spikes, drops, microstutters, G-sync, Freesync etc.