For CV1, will 90fps be required for low persistence?

everything seems to point to 90. but maybe they might have alternative refresh rates available. either way it seems in practice you have to hit that rate every frame or it get's a little ugly. turning off low persistence gives a blur worse than dk1 (at least more noticable and made me really swimmy in the head) so that's not really an option either to run at a lower refresh rate without low persistance. who knows they may have some voodoo going on behind the scene to blow us all away. I'm deving on a gtx650 (can't afford a higher card just yet) so I've included quite a few options in my game menu to enable it to run as fast as possible and so for those with higher cards the settings can be raised for better graphics, I guess that's all that can be done is plan for the worst case scenario and provide options for those have the high end hardware..