Without being an expert with EMF, these are my thoughts and thoughts only. The metal casing of MC cables is about as good as EMT, which is I don't think either are to effective with EMF. If the conductors in the MC are rotating that will improve it over the EMT. The only conduit system shown to help with EMF is IMC or RSC, the only ones providing a thick enough sheild for 60 Hz.
With that said, EMF dissipates in a square of the distance, so another fix could be using recycled tires for walls stacking them horizontally and running the wire up through the center then bonding steel belts. This solution not only makes the home EMF friendly, it can be LEED certified for the reuse of materials and can qualify as the city dump.
On the other hand, in proper wired buildings, I have found almost no evidence of EMF in the wiring with the exception of panelboards and meters (due to separation of the conductors). So a solution for an EMF friendly home would be to intellegently place the load center(s) and meterbase in areas of infrequent traffic, then simply telling the owner to be careful of the devices used and installed (open motors, electric heating units, etc.). Overall, I don't worry about it other than to use EMF to track down problems in wiring.
