New build in first post that has script toggles for each part:
pp_loaded - toggles whether the entire post processing system is loaded or not, turning this off and on essentially reloads your shaders.
pp_fake_hdr - Toggles the fake HDR.
pp_effects - toggles whether your effects are used.
pp_motion_blur - toggles motion blur.

Also, for this build i've made a simple OS toggle menu (using TextBlock's already in OS) that is accessible when you are in the menus by holding down left shift and using the top row number keys to select your options. This is seperate from the post processing code and can be easily used by other components that want to be able to toggle their bools . The bools don't need to be script globals either, just pass your bools pointer and the text you want to go with it in the RegisterToggle function and it'll get added to the list.

Also added a Vignette shader and my attempt at a simple Chromatic Aberration shader.