Weight mapping copy works fine for tight and reasonably tight garments. The weight information is valid for the location where the vertices of the donor are. Any extrapolation to garments that fit less tightly is a guess.

Original 'sphere' mapping is much more restricted than weight mapping but because it defines the weight information on the basis of the xyz coordinates. Depending on how the falloff zones are defined, the weight info for the location of the garment vertices may of may not be usable.