DISQUS

Do URIs actually require more upfront thought than other schemes, though?
More than localized, context bound schemes - yes.

But the really cute thing about URIs are that they form a sort of federation of separate localized context bound schemes. Each URIRef carries around inside itself both the global name of the local scheme and the name within that scheme - all in a reasonably familiar, readable and compact sequence of characters. So no, I don't think URIRefs can require more upfront thought than localized schemes other than the trivial issue of deciding on the first part of the URI used to prefix names in the scheme - to make them globally unique.

In theory, when you merge data, you determine that the same URI has different referents via logical inconsistencies; in practice you have domain experts and data modellers look analyse the data (just like you do with relational database integrations).

Surely, if two or more datasets use the same URI to denote different resources then at least one of them is simply wrong - it is not using the URI in the way that the URI's original minter intended. In practice, you need to have your domain experts fix up the data before the merge.

(3) and partly (2): Don't point a gun at a person unless you mean to kill them. Don't point an HTTP URL at a resource unless you mean to retrieve it (or otherwise access it using the Hypertext Transport Protocol). For "real-world" things use tag: or similar URIs.

This will make the distinction clearer to people and will also avoid wasted network traffic when attempts are made to retrieve the resource.

I realise I'm in a minority with respect to this opinion on the use of HTTP URLs but I've yet to see a coherent argument against it.