I just upgraded to 64 bit Win 7 and Sonar 8.5.3 PE, I'm dealing with the problem now. Things have changed since this thread ran.
I'm having some problems getting it to work in 64 bit even after all the firmware updates and new 64 bit Fantom VS Installer.
Any new developments?
 
I loaded a new project inserted the Fantom VS and the Editor loaded with all the menus and worked. I then deleted the Fantom and loaded Fantom VS #2, the Editor loaded with no patchs in the channels and the drop down lists were all GM items. I deleted the synth and closed the project. I deleted Fantom #2 from the file directory-VST Plugins and it vanished from the plugin manager also.
I opened my older project again, deleted the Fantom from that project and inserted a new Fantom VS in which I rebuilt my prior instruments and settings. I saved the project, closed it, re-opened it and all the patchs and settings were retained. So that's workable now.
The 64 bit Fantom Editor loads differently than the 32 bit did. X-ray doesn't work with it, when I first open the project with the Editor open, I can play notes and do adjustments, if I minimize the Editor and open it again, I get no sound while it is open, and when I minimize it, all the notes I tried to play while it was open, are suddenly released and sounded. Some kind glitch going on there.
See the Update Path Thread.