"They import to the location they were at during export."

Usually. I've met some scenes where the busy DUF file calls, scales, positions and textures its multiple DSF objects. Think big, big Poser CR2 or PZ3...

Upside, an un-compressed DUF, like DSF, is usually plain-text, resembling an over-grown MTL, PP2, CR2 or Poser MAT file.

Down-side, may need equivalent of PhilC's Classic Poser file editing utilities to study, never mind edit, lest structure be munged by detail, per 'Wood for the Trees' effect...

( I'm still searching for an affordable in-situ FBX editor: Recent versions cannot be studied by classic FBX Toolkit, while I've yet to edit an FBX ASCII file and have it 'work'... )