Main problem with a zero-A pose in the fitting room is the automatic grouping. Sometimes the collars do not have a ring of facets under the armpits.
Weight maps can be (more or less easily) rectified with a few brush strokes. Unwelded mesh is not so easily solved. That's why I use a separate figure specific grouping script when I make MD built garments into conformers or hybrid rather than rely on the Poser provided grouping.

It still gives me a more or less automated creation process without destroying the garment into T pose.