Hi chipp,

That might be a tricky one. I'm pretty sure .abc only works with splines, not nurbs curves ... and while I'm not a specialist in this kind of stuff, I think it's 2 different data type.
My best bet would be Maya or Houdini, they both can handle nurbs data (igs ? ...), and they both have good .abc exporter.

But I'm pretty sure you also need to somehow convert/resample the curves into splines before exporting them.