I just had mine installed and I am going to continue to use my Microsoft streets and trips to plan routs. The MS cost $99, including the GPS receiver and it even has the private and small sectional roads here in Canada, it is excellent.
From that I went to the D3 and it doesn't even have some highways, it routed me to a 400km route home, where I had a direct highway that was only 160km. I could not believe what it was doing. Further it plots me about 100 yards off the highway in a lot of rural areas where I drive. I have played with the speed settings and the multi-route, nothing makes