The 2408 seems to be more adapted for legacy expandability. You could pry use ADAT out from the 828, unless you are already utilizing the ADAT in on the 2408 for something else, although the 828 is only 8 channel ADAT out (at 48kHz and under and 4 channel at anything above) whereas I think the 2408 is 24 channel ADAT. Although, who knows ... maybe your recording software can recognize both drivers for the two units and allow you to configure for multi-card setup. If so, you may need to sync the two units via word clock.
Just throwing ideas out from speculation, as I don't know for certain.
-Ken
