Well, the eccentric part of the lift is what creates most DOMS and causes greater CNS fatigue.
"How does accomodating resistance theory ala Westside differ from variable resistance theory ala Nautilus?"
Because the nautilus machines are based on averages which hardly coincide with the VAST majority of trainers. For most people, the restistance will be too big or too small. Machines in general are also inferior in that they render the eccentric part [for bodybuilders, essential] of the lift useless and don't make you stabilize anything. The construction of these machines also leaves a lot to be desired.
MHO,
-Zulu