Madscientist:
They key reason why Digidesign brought forth the MBOX is to cut into the semi-pro studio market with a more affordable solution to the Digi002 and higher end ProTools models. This is to make headway into an attack on the other sequencers which have been cutting into ProTools' market share over the years. It is also a way for Digidesign to position themselves in such a market should Apple make Logic a greater competitor to ProTools in the digital audio recording market.
Anyway, to answer your question, I think the converters on the MBOX are decent, and should do the trick. However, I don't know the analytical data yet on the convertors used, which is also key when deciding a system like this.
MBOX: 24bit/ 44.1, 48kHz sampling rate
Digi002: 24bit/96kHz sampling rate
If you're looking at sound quality, the bit depth is more important than the sampling rate, which I can argue is a moot point once you start recording at 48kHz. The Digi002 will use up more computer resources than the MBOX, but the 002 contains more power regarding the support of FX, processing, etc.
Sonically, I think the argument is moot. It's more about what you want from your card in power, and how much money you have.
Sincerely,
God