apart from the obvious differences between the 800/400 (rack size, bus power, etc)... are there any differences between each of these units? different AD/DA converters? mic pres? etc? and how do they work with logic 7.1.1? looking at the 400 for a portable interface... (running live tracks with multi-outs--possibly tracing on the road...) and the size and bus-power is a great feature... but what about the focusrite units (with native plugins on outputs), or the MOTU units? anything else i may be over looking? so appreciate all the input on this one. best tv