Go away, Sean
Seriously, though, you are quite correct about Tomtom on the Chinese double dins or any other system running WinCE. Its a well documented fact that anything beyond TT6 will not work for a variety of reasons, primarily audio clipping. TT6 is currently getting the pension and is well beyond its sell by date.
In any event, iGo is far superior IMHO. Tony (Fry) has a great version of iGo over on the MG7 double din thread.
I would also recommend purchase from Sean (Radioguy) due to his excellent warranty. Its impossible to beat unless you deal in a bricks and mortar shop (and pay the premium for doing so!).