It seems that special chars from XML like > get lost in the putPage()-call (the other direction works fine, though). I am claiming this is a DokuWiki-Bug as this problem exists as well in DokuFS as in DokuVimKi as in NoteFinder which use different XMLRPC-implementations.
I am not sure if it's a bug of actually a fault of DokuWiki or if it's rather
http://scripts.incutio.com/xmlrpc/, the XMLRPC-implementation DokuWiki uses. I have no idea (yet) where the chars are lost.
At least in the Ruby-Client I see lines that replace > by >. In the server I see no line that does the conversion in the other direction, but I don't know if that would be necessary.
I will continue debugging this and try to find out where these chars are actually lost.