Actually, believe it or not, I did manage to export a prop from Bryce. It took me a good week to figure it out, but I did it. How? I exported it a piece at a time! As long as each piece is made from only ONE terrain, it can be exported from Bryce as an OBJ file. Once all the pieces were out, I reassembled them in Poser, and then exported all the pieces together as a combined OBJ file. So it IS possible. But it's a LOT of work, and I wouldn't recommend it unless you're really desperate :-)