Yes, Eventide should definitely get rid of any mention of Mac-support via vsigx on their documentation. They still send flyers that mention vsigx, that should not be the case.
It seems from archives that things work fine on Intel Macs. If you have problem with the serial connection (may happen especially if you are working on G4 or G5 with a windows emulator), it's possible to communicate with the Harmonizers using the Sysex commands (the same that are used by vsig) – works both using the MIDI or serial hardware connection.