An update: as of r501 there are two new features in the Layers Bar modelled on the option C approach.
Please back up your projects before trying them - they make complex project-wide changes, and in particular, currently replicating layers cannot be undone. If anything goes wrong it's possible they will make a real mess of your project, so take care.
'Replicate layer across project' will copy the layer properties and the structure of all sub-layers (and their properties) to all other layers in the project with the same name. This means you can easily update layer properties, as well as adding, moving and deleting layers across the entire project. Note however that due to the aforementioned problem, renaming a layer will be counted as deleting the layer with the old name and adding a new layer with the new name.
'Rename layer across project' is designed to solve that last problem by renaming every layer in the project with the same name.
Let me know how it works out for you in your real projects!