I have added a few custom POIs to my Navman and they work well. I tried to add a alert as a wave file. All seemed to work well, but I don't hear the alert when the visual alert appears. First time on a forum, so excuse any etiquette issues.
I have a Navman75T which was brought as a replacement for a TomTom, worst decision I ever made, the tom custom POI sounds and icons can be changed without having to reload the file, it is a pain...