I use RouteConverter for some other things. Have had no issues with it or its conversions to/from various formats. Has the benefit of showing the data on your choice of a base map. You can also easily delete (i.e. pre-takeoff or post landing points) (or add) position points if needed.

It opened one of my igc files and saved it to a kmz. Only issue was the need to select the "Position List" drop down list.