As far as I can tell, after a few minutes of testing regarding the UADx SSL 4000E Channel Strip support:
1) Loading each section is like inserting a single native UADx SSL 400E Channel Strip which means if you load the filters, gate, EQ and compressor you'd be loading 4 of them which sums up the "color" or "tone". The CPU load doesn't scale up equally, though. Loading all 4 sections is like loading two native UADx SSL 400E Channel Strips. Not bad in my opinion.
2) No mic preamp but each section uses the line preamp which is less colored. This might be good because you'll be probably stacking all 4 sections and that means a better balance "tone-wise".
It would've been nice to have the mic preamp and VCA fader for the preamp and drive sections respectively. Please consider this @
Softube