Yes, that’s a good solution for the G5. Just need a Toslink to Miniplug S/PDIF optical cable, or a Toslink to Mini Optical Adapter for the Toslink cable.
My AJA Io is still hooked to a G4 DP 1.25 MDD, so I’ve been using an EZBus digital mixer/interface to connect with the AJA Io via ADAT. Lots of flexibility on the mixer side, plus a very clean in and out with the Io.
The EZBus also interfaces with the Mac via USB, so that path is also available for use with FCP or other applications. Several other mixers and DAWs can also do this, some with FireWire. None interface directly with FCP, but maybe the speculation that Apple would come out with such a device, or at least allow developers to access the necessary code to enable their products to work with FCP will yield something at NAB.
…Tom