The topographical features in Navbox appear to be accurate enough for en-route navigation. I've never had a problem. Temporary waypoints will be as accurate as you can read off the chart or acquire from some other source (e.g. Microsoft Autoroute) and should be easily accurate enough, but always double check for typos and do a "gross error check" that the waypoint appears where it should relative to other features.
Haven't touched the CRP for over 5 years.