I can confirm that the coexistence of Itunes 8 and MC 13 are not causing crashes.
At the very least, Glynor and I are managing our libraries with MC, then jockeying some things so that itunes can then sync what we managed with MC. This method, though kludgy, is working for us until a true sync feature or plugin within MC sees the light of day. I have to do it this way since Itunes, in all of it's inferiority, can't use my flac files (99.9% of my collection).
If I was an mp3 kinda guy, I would just point MC and Itunes at the same folder on my NAS drive. Itunes would be used to sync to the ipod and MC would do everything else.