Davey Shafik points out a second option for the saveXML function of the DOM functionality in PHP - an option to restrict the use of "empty tags".
This argument currently only supports one value which is the constant LIBXML_NOEMPTYTAGS. This option makes sure that you do not end up with <tag /> but instead, <tag></tag>. This can make things easier if you need more predictable text to perform other changes on later.
He also noticed some other changes that the option made in his XML documents, specifically a size increase issue with spaces. Code samples are included to show these differences.