Are you marking your own neutrals in some way? Is white THHN available in striped varieties? Not in my area, at least off the shelf. The mistakes happen when care is not taken in labeling each end of wires. This thread has me wondering what is available for neutrals from the factory.
The Romex in the conduit idea seems to me like it would add more difficulties than it would help, since space and code issues limit such installations severely.
