Here is a difference I have observed. Downloaded the latest RC of Immunet Protect. A little popup in the corner of Norton notified me that the file was safe. No popups during install.
The same file with CIS, cause about 20 popups during install. I lost count, they were coming so fast. I finally put both d+ and the firewall in training mode.
Again, it is not the popups for malware that bother me. It is the safe programs that cause D+ to go absolutely nuts that wears on me. While I think both CIS and NIS are great, I think NIS has a large usability advantage at this point.