I finally received my new 3790LMT and upgraded it to 3490 specs. All went well thanks to all the information gathered into this thread, it was very easy.
I was really concerned about the accuracy of the Satellites after reading that several people had problems.

Well, I have a PCB v11 and the accuracy was 3 meters with the 3790 and now it is 4 meters with the 3490. Both were upgraded to the latest software.

Not sure if I like the 3790 or 3490 better. But since I upgraded to the 3490, the GPS crashed a couple of times...