I know a videographer that has a PD150 and a Casablanca Kron and says that he doesn't use the firwire to capture but rather the svideo so that he can control the audio. He says that the image quality is equal to capture from firewire with the freedom of running the audio through is mixer first before processing it in the NLE. Is this a viable solution? Or is this guy off his rocker?

In almost all cases analog is no match for digital (S-Video vs. DV). At the very least his program is going through two extra steps. D to A conversion to send the program out via S-Video and the Casablanca does an A to D conversion to be able to manipulate the video. The extra steps will add noise and lower the S/N ratio. I would only do it as a last resort.

Why not do both? No, I don't mean use the S-Video out. He could use the firewire out and still record sound out independently if he wishes. I don't know anything about Casablanca, so this might not be practical but on most NLEs one can always record the audio independently through a mixer and add it is as independent track.

that's what I figured, but this guy is not your most snazzi person when it comes to technology. I figured by the very least he can capture IEEE 1394 video (digital) and digital audio and split it in the NLE and then use a sound utility to tweak the audio track and recombine...but I guess he is used to the linear editing world, I think he has recently given up his BetaSP in favor of DV.