Some beta testers and I tested this application for a long time. I believe that the results are relatively error free. But I can't give you any guarantee that your positions are correct. Be careful with the output and, like all good navigators, use common sense and always cross-check your position by other methods and systems.
Map data from OpenStreetMap, Licence is CC-BY-SA
This product was developed using parts of GEOTRANS, a product of the National Geospatial-Intelligence Agency (NGA) and U.S. Army Engineering Research and Development Center.