Ive always thought that for how many aviable components you can craft a riot geat shield with, there is little variation between them, which i feel takes away some flexibility and use from this particular armor piece and leaves little room for experimentation.
Two properties matter when selecting riot shields components, their inherent Armor Penalty and the block capability (not % chance) of each, which ive verified and made this to ilustrate my point. I feel caparaces have no particular stats that make them stand out from metals plates, the former being able to block more damage and having the possibility of having their Armor Penalty reduced with a feat, with the expemption of Psi crab and beetle they offer no particular benefit. (all materials used were 100q)
So my suggestion would be maybe change the properties of caparaces and metal plates when used as components for this slot, perhaps
providing an aditional block chance increase but decreasing the ammount blocked, or allowing them to block different sources of damage more eficiently.