I'm just going from what I learned from the H7 update, really. Kam187 said not to apply the CSC if we didn't want Italian operator settings, etc. The H7 CSC .tar file only contained "cache.img", and this file is also included in the "one package" file for H8, hence why I removed it from mine before applying it.
I believe the CSC is one of the factors that comes in to play with regards to firmware update checking via NPS, and it also might determine which apps are available in the Market.
Kam187 is probably more the expert in this kind of thing, so I'll happily defer to him for a better or more accurate explanation!
Chris