Yes, iGuidance is widely supported by the CarPC user community in USA/Canada, and only few CarPC enthusiasts venture to try another program. This has more to do with the ability to integrate it into CarPC front-end software, rather than with actual features of the program itself, though. Since you are familiar with CoPilot, I would compare iGuidance to CoPilot always used in "Guidance Mode". (The CoPilot's "Planning Mode" is something unique to CoPilot, and it offers advanced trip-planning features.)
While CoPilot has (much) more features than iGuidance ever will, iGuidance has an edge on map data and routing quality. There is no such thing as a perfect program. It's always a matter of compromise when one tries to find the best product for himself/herself .