When overriding a community extension should I use the original namespace or my own?

Question

We work with a large number of community extensions and frequently override their behavior with small extensions of my own. So far I've been using a naming convention of app/code/local/{MyCompany}_{OriginalnamespaceModulename} for my overrides, which is useful for clearly putting our modifications in one location.

However, I've also frequently seen where the original namespace and module name are re-used (e.g. the original module is app/code/community/{Namespace}_{Modulename} so the overriding extension is named app/code/local/{Namespace}_{Modulename}. This seems intuitive; except for when 3rd party extensions want to be installed to the local codepool. In our case we do have a fair number of 3rd party extensions in local, making it a bit of a goose chase to check if they are a "full" extension or just there for overriding a community extenion.

So what's the best practice? Is there anything wrong with my format of {MyCompany}_{OriginalnamespaceModulename}?