firewire interfaces were preferred over USB ones... I do not know how this is these days with Intel-Macs.
In the past it was said, that USB can only transmit several instruments as one track (as a summation) and firewire gives each instrument seperately, though recorded at the same time. This is relevant, if you want to edit tracks seperately. (Though the audiobox has only two ports, you might want to use your two microphones at the same time to get better control over the drum sound, e.g. one for overall sound and one for the bassdrum, which can be useful, because the bassdrum tends to get very quiet, when using one microphone. You could instead put the mic in front of the Bassdrum 50cm away, if you want to use only one mic, though. This will result in a loss of bass frequencies, but in a gain of the bass volume).
Also I think firewire is better implemented in Macs still in the Intel-era (didn't 10.6 have problems with the USB ports?).
If you choose the presonus "firestudio mobile" over the "audiobox", you will pay 100 more, but you will get firewire and most probably better preamps, I would check, because I do not definitely know. (if one need 92kHz instead of 48kHz is another question...). But for the price of a firestdio mobile or even less, you can get a used firepod, firepod FP10 or "firestudio project"... if you really need this, is another question.
For future expandability the firestudio mobile is intreresting too, because it is cascadable (right english word?, I mean you can connect two firestudio units and get 4 tracks but have only one cable that goes to the mac. I think daisy chaining is the right english expression, someone help me?).
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