Alright in regards to how much fps the eye can see, let's assume there is no such thing as a plecebo for this arguement. I can see a 45hz CRT flash easy, and can get headaches by staring at a 60hz LED for too long. While I can't probably "see" flashing beyond that, I can very well sense it and its like that annoying feeling I get by starring at a red laser pointer.
Motion blur fixes these problems by making things appear more smooth. Thats why incadecent bulbs dont give me as much headaches as LEDs even though they can both run at 60hz. Incandecent bulbs have a terrible responce time, taking some 100ms to fully go from bright to dark while LEDs do it on an order of microseconds. Thats more inline with color, shade, and persistance of vision perception rather than how fast your eye can see. You won't notice two close shades of color at 60hz as opposed to high contrast black and white flashing at 60hz.
Does it help with responce time? Yes, but with exponentially diminishing results. A 60hz is obviously better than a 45hz, but there is debate when it comes to 144hz vs 60hz because the results have a difference at which we cannot percieve easily without thorough investigation. I have no idea how much fps the eye can really see, but even assuming it's infinite, you are still not going to get much after a certain point.