Worth noting that directors use high speed film to portray a feeling of confusion. The lack of motion blur gives that sense to the scene. E.g. the opening scene of Saving Private Ryan uses this effect.
The effects in the battle sequences of SPR are not a result of high-speed film per se, but the result of altering the effective shutter speed of the camera to reduce motion blur (switching from 180 degree shutter to 90 or 45 situationally). The scenes were still shot at 24fps. If you have a digital video camera with manual shutter control, set the framerate to 24fps and set the shutter to 1/200 and you have instant SPR.
This effect is now very common for action scenes in movies and also tons of music videos. Very easy to spot once you are aware of it.
You are actually speaking of the same thing, "high-speed film" similar to a "high-speed lens" doesn't actually affect the framerate, yet rather how fast it can produce an image from a certain light-source. It's simply more sensitive.
Now, you're correct that the actual effect is done by changing the shutter speed. but the loss of light is often compensated for by using a faster film, since using a larger aperture has more significant effect on the scene in the form of DOF.
