I'm a Linux person, and I don't have relevant things to say for Windows. But since we're talking about xmodem transfer, the standard Linux program that does xmodem, ymodem, and zmodem reception ("rx", "rb", and "rz", but deep down it's the same program) has the annoying habit of dealing with fatal errors not just by quitting but by deleting the file that it was receiving first!
While I forget whether this led to trouble with BLU, with UsbWidEx, there's a disagreement between the way rx does xmodem and the way UsbWidEx does it. This disagreement arises at the very end of the transfer, and rx has a tantrum and fatal-errors. The hard drive image you spent many minutes downloading (all while wondering if the drive itself will survive!) is deleted immediately. It's very frustrating!
The quick-and-dirty workaround is to go to another terminal window while the image is being transferred and make a hard link (plain `ln`, not `ln -s`) to the file being downloaded. rx will unlink the original filesystem entry for the image, but your second entry is just as good. The image itself will be fine no matter what rx thinks about it.
