I have stealth PPF full body on my X and had ceramic put on top. In my opinion, there is no addition protection given by the ceramic but it just makes it look nicer. The water beading is so nice in the rain.
I was hoping that the road dirt would just spray off using a hose with the ceramic but it does not make much of a difference that way. Make sure the installer gives you the ceramic recharge spray as you will need to reapply every 6 months at least.
If I was doing it again, I would do the ceramic coating myself as soon as i got home with the PPF installed (while it is still very clean). At the end of the day ceramic just replaces frequent waxing, in my opinion.