I’ve been doing a lot of research and the Blackmagic Intensity card seems very compelling. It just started shipping so there’s probably no reviews for it yet. For your deck, you could buy an HDMI Sony HC3 ($1100) and the Intensity card ($250). This $1350 combination takes care of most of your dilemmas: you get a new deck, capture is all digital (it doesn’t use the analog component outs, the HC3 is connected to the card via HDMI which has both audio and video, control is still over firewire), you can capture as uncompressed HD or downsample to DVCPRO-HD which Final Cut Pro handles easily without needing a RAID, the card also has an HDMI out port so you can monitor it on any flat panel display with HDMI (your Samsung probably has it).
I’m really considering this setup, and unless the Blackmagic crew know otherwise, this camera-card combination will solve a lot of my HDV pain at a reasonable price. Since it doesn’t sound like you need SDI for anything, the only issue is if your G5 is PCI-X or PCI-e.