Right. I think most of us will agree that "image quality" is a subjective criterion, especially if the paper specs are very similar. But, when it comes to the frame rate, it's a lot clearer (OK, some companies will fudge the actual quality of their HFR ... is it 1080 or more like 720?). And, of course, one can shoot 1080 and use Twixter and so on but it's just not the same.... One guy owns both the FS7 and C300 II and likes the C300 II image better. Why to tell him that he is mistaken? Another guy rents based on his requirements and the project says 4K 60p. So he can't rent the C300 II. So horses for courses and one uses what is required by the project. I am fine till this point...
BTW, I remember seeing the first slow motion replays from the 1970 World Cup. For a kid, that was such an amazing trick. The res sucked and the image stuttered but it was incredible compared to what preceded it. The 1966 WC was still shown in B&W. Then, for the 1984 Olympics, ABC introduced "super slo-mo" and that was a pretty big step forward as well.