My one original sentence pretty much exhausted my knowledge on the topic. I remember reading a review of the Fuse back when it was new, and the conclusion was something along the lines of, "What wonderful video capture for only $500." And I wanted one, but never bought one.
I think, but am not at all certain, that the Igniter was better. The Fuse does not have sound capture. It relies on the host machine for that. Perhaps the Igniter adds sound capture?
I have zero memory of the software. I would guess some version/versions of FCP and maybe the program that shipped with the Radius cards, the name of which I can't remember.