I have a Xl1, and did some long duration shooting with through firewire, and the audio became out of sync. I not 100% that it was the fireaire, but I would recommend that you get a capture card for the computer you are going into. Blackmagic makes some good capture devices, they have the Intensity Pro which is PCI express 1x card, and a USB video recorder. Then you could just run, a 50ft siamese video audio cable from each cable to your control point. Which is cheaper than a 50ft firewire. And the quality will be better since the audio and video won't be compressed down one cable.