So they finally did it. Sony has enabled a write back function on the PDW-U1. Now MXF data can be written back to the U1 through the OSX XDCAM transfer software. They have also released version 2.9 of that software. In my online videos, I show how to write back to the ProDisc from Final Cut Pro with a PDW-700 or PDW-HD1500. Now this same process will work with the U1 through USB. Sony has posted the software on their site here – Sony XDCAM Downloads.