I think "as near as makes no difference" is not sufficiently well defined for the Turing-test-equivalent scenario I'm quoting. The question of "makes no difference to whom?" becomes important.

This is a problem for the traditional Turing test, as well... a great deal depends on who the auditor is; some people turn out to be surprisingly undiscriminating. (Or, well, it surprises me.)

But yes, if I don't take the Turing test bit that I quoted literally, and instead think more abstractly about a sufficiently precise and reliable functional test, then I agree with you.

Actually, I don't consider structural isomorphism necessary in and of itself; functional isomorphism is adequate for my purposes. (Though that said, I do think that an adequately functionally isomorphic system will tend to demonstrate a high level of structural isomorphism as well, although that's not a well-thought-through assertion and my confidence in it is low).

I'm just not sure what such a test might comprise in practice. That is, if I'm in charge of QA for Upload, Inc. and it's my job to make sure that the uploads we produce are adequately functionally isomorphic to the minds of the organic originals to avoid later lawsuits, it's really not clear to me what tests I ought to be performing to ensure that.