I'm not sure why the Jquery version allows negative letter spacing yet the WordPress version of FPD doesn't... but as a designer Im shocked this is not a standard feature.! I kern practically every line of type I set, as most letter pairs are shit or just dont even exist!
Also, it would be a great feature to have an Uppercase, Lowercase, Small caps, etc. toggle button added.
Cheers and keep up the great work!~
* Regarding negative letter spacing, I was referring to the Product Designer in Admin (not the front end as that already allows negative letter spacing)
Will come with the next update, that allows negative values for the "Letter Spacing" input. The text transform options will also be added soon.