I use the Inspire, and I've *heard* that the preamps are the same on the two units, but I could be wrong. The preamps on the Inpsire seem good to me, but there's not a ton of gain - probably enough for that mic, though.
With the Inspire, all the controls are in a computer program, while the Firebox has knobs and stuff on the unit itself. Personally, I don't mind using the computer to control the Inspire, because I'm sitting in front of the computer anyway.