Well, to quote myself:

Furthermore, 'the difference in the pattern' seems both somehow hard to quantify and more importantly - it doesn't look like something that could have a clear cut-off as in 'if the pattern differs by more than 10% you are a different person'. At any rate, whatever that cut-off is, it still seems pretty clear that tenoke!2000 differs enough from me to be considered dead.

Or in this example - enhanced Eliezer (imagine that the number of enhancements is massive) and non-enhanced Eliezer who can't even begin to think about the stuff that enhanced Eliezer does.