Attached Link: http://www.verlsnake.eu

I know that I can save an animation made by clothifying a prop to the .pz3 format; and it will be read back correctly into Poser; but unfortunately not into DAZ Studio 3; is there a way to export 'Clothify Animation' from Poser to other 3D apps ? Or can it only be exported via a series of keyframe files ?

You can export it as point-level animation, and some applications can import such, but be warned that disk space required for this kind of thing can be VERY large.  Basically you export 1 OBJ file per frame.  Here's a thread that discusses the mechanics:
http://forums.cgsociety.org/archive/index.php/t-444692.html

Yes one OBJ per frame is about your only option. May I ask what do you want to do with it in DAZ that you can not already do with it in Poser?

To me, one main attraction of DAZ Studio is its relatively new, integrated Decimator Plugin; it allows me to do Polygon Reduction on figures in a way that preserves animations, morphs, etc.; another workflow of mine is: Export .obj files from Poser for each keyframe of an animation; then do polygon reduction on these .obj files using standalone 3rd party polygon reducers; BUT: The polygon-reduced .obj files have very probably NOT the same vertex count and order; the DAZ Studio Decimator allows me to export polygon-reduced .obj files which have exactly the same vertex count and order ... That's why I'm so keen on importing Clothify Animation into DAZ Studio, too ... Maybe importing a series of Poser-exported .obj files could be a way to go ...

Quote - the DAZ Studio Decimator allows me to export polygon-reduced .obj files which have exactly the same vertex count and order...

This is impossible.  I suppose you could remove face information, but polygon reduction methods don't do this (and it wouldn't be very helpful to do this anyway, because it would only make a hole in your model where faces are removed).