Redactor currently uses <br> tags when doing a line break. Can it be told to make those into <br /> tags instead. I had a problem elsewhere in a site trying to build an XML feed that didn’t like the HTML version of the line break tag.
It can’t unfortunately.
However, I would suggest using cdata in your XML feed to avoid breaking when it encounters unescaped html. Even something like & can break XML feeds otherwise.
MODX comes with a cdata output filter to make that easy:
<element>[[+data:cdata]]</element>