As Gold VIRP member changing over from Tyre. I think you have the core functionality pretty well cracked.
I was trying to find a solution for our friends that are joining us in a rental car and now way to load my routes. Which led me to assess the Sygic App.
I created a route in MyRoute-app and set the navigation function on. The following was my experience with Sygic
1. Despite having one main route it kept telling me to turn at every possible turn both left and right. I can only presume it had reversed the start and end point and was trying to get me to turn around though it didn't say 'Turn around as soon as possible.
2. I then cleared the route and created a destination in Sygic.
3. On a righthand curve in the road it told me to turn right
4. I chose not to take the route it suggested. Rather than picking up the next primary route (the one I chose) it tried to send me down several small minor roads and to difficult junctions back to the original route it had selected.
Is it possible to use My Route-App with Tom Tom Navigation App?