I have only used the NDS app in this country and I don't find it as appealing to the eye as the Go app, just my preference but routing is the same as the GO app so far.

TTGO
1. Very satisfied.
2. Car.
3. Very reliable
4. Very good map coverage although a local beauty spot (Blaencuffin Canyon near Pontypool) is missing. Also missing in all other apps.
5. Most of the time, sometimes it likes to take narrow country lanes no matter what routing method is chosen. Applies to all other apps as well
6. U.K, USA, New Zealand and, in walking mode, Hong Kong
7. No
8. Sygic truck, Sygic car or Navigon would be my preferences should TomTom be lost.