This is just me talking, but I'll never trust Navigon. I was one of the few people to buy one of their hardware GPS units several years ago. Not a few months after that purchase, they announced that they would strictly focus on software and iOS applications. No more map updates or technical support for their hardware. When I had an issue after months after that, there was no customer service to be found. I was SOL.
I know that the speed of business and technology moves fast, but you'd expect a company to at least provide a basic level of customer and technical support for their previous-paying customers before totally cutting them off at the knees. I eventually sold the hardware to Gazelle to something like $30 and got a Garmin device for trips (I use Waze around town).
I have zero experience with their IOS apps, but just a warning about the kind of company they are (or were).