AirNav support was really good a couple of years ago but I suspect the developers have now moved to other things and it is on the backburner.
Having said that I find it excellent for VFR but not nearly so good for IFR (although they say it will do IFR). The Flight Schedule it produces is good in the cockpit for VFR. I still put my IFR plan into Airnav and let it calculate distances speed and wind - then transfer the information a manual sheet.