Indirtwetrust, I am almost positive you are right. I remember asking the difference between the boards because I ran into some issues upgrading a 2 to a 6.

Getemup - Like Indirtwetrust said, these boards are for both AC and DC. When going through smartfast there is an option in parameters to set the board to work for either. I am really curious now, keep us informed on what you find, usually these upgrades are pretty straightforward.