Just as an update: I have received a couple of perfectly accurate comments that the documentation for xia2 is inadequate. I have started a xia2 wiki page on the ccp4 wiki:
http://ccp4wiki.org/~ccp4wiki/wiki/index.php?title=Xia2
Currently this is fairly weak, but the idea is to focus my documentation efforts on here. If you wish to mirror the changes on any other wiki please feel free...