I use meld too. But afaics, meld 'syntax aware' is very different from from difftastic.

Meld takes a diff, and applies syntax highlighting over the diffed files. It additionally highlights the changed characters in a line. Git diff, vimdiff and probably others, do this as well.

From the demo, I understand that Difftastic first applies syntax and then rebuilds the patch over that. Being aware of line wrapping, changes in nesting, moving codeblocks into functions and so on.