And the same with RNS in Canbus.
I'm sure the standard HU will work just fine even if navigation is still activated in the CANBUS. Because mine had the RCD500 in when I bought it and when I fitted the RNS510 later, navigation was already activated (previous owner had his RNS510 removed prior to sale but not deactivated in the CANBUS).
Although seeing as you will need to deactivate the cruise you may aswell deactivate the navigation at the same time