Feel free to download a few 2k high frame rate raw Sony F55 files for low light noise/grain testing and read my blog here:
I updated the Sony PMW-F55 camera with the new v2.0 firmware and enabled high frame rate (HFR). I have been patiently waiting for this feature to be added to the camera.
I shot a bunch of test clips in low light during a thunder storm deep in a dark wooded area. I wanted to see F55 HFR 2k raw in a worse case scenario. I brought the MXF clips into Sony's free "Raw Viewer" software and found the noise to be acceptable, even when grossly under exposed.
Check it out for yourself and visit my blog for original untreated raw downloadable MXF files straight off the camera for your own testing.