There are numerous sources that confirm that the S9 is capable of this.
[Unfortunately as i am a lurker and do not have an account i cannot post links yet so you will have to search yourselves but the sources are numerous]
It is quite obvious that Samsung limited this feature, perhaps in order to segment their branding or because they felt that it was too unstable.
Does anyone know if there is an existing mod for this?
I have a 144hz monitor and would love to start capturing footage I can watch at a higher framerate.