I'm not so sure ... I added it but it needs a little more work.
First, you need to have a key binding - as there isn't one by default.
But then it would be good if the line numbers would turn on/off on both buffers at the same time - as is you have to manually switch it on for both.
Worse, it doesn't remember the setting - so when jumping between versions in backup history for example you have to keep turning it back on.
So, while I'd like for diff to support SpecialChars and line numbers (and highlights, and, and...), a bit more integration is needed to make these nice features.