I've just committed an experimental feature in my SoC branch which let's you specify the frame ranges which F-Modifiers are applied for. This allows for interesting effects such as:
Using this feature, it is now possible to for example have different noise-profiles for different parts of the curve, which makes it possible to do animate camera shake for example.
This is kindof a workaround for not being able to keyframe these and perhaps also the fact that these can't be chained together in some nodal workflows where the Limits F-Modifier may have been of a bit more use for such manipulations.
Nevertheless, I'm keen to see how useful this turns out to be.