I think the general answer is, it depends. Hopefully this tool gives a dev ready control of what kinds of differences to hide/show. I'm actually not convinced

I think the general answer is, it depends. Hopefully this tool gives a dev ready control of what kinds of differences to hide/show. I'm actually not convinced of the concept of semantic diff (not talking just about this tool specifically)... when we talk about code that is different but equivalent, I think we're talking about elements of style. It seems to me that it would pretty much always be better to normalize the elements of style considered insignificant, rather than hide them just in the diff tool. That covers diffing as well as viewing/reading the code. If you don't care about a particular element of style then either it shouldn't be coming up much or I think you'd be better off using some kind of enforcing/fixing linter.