Some DeltaXML customers are using DeltaXML to compare documents represented as XSL-FO. There are many sources of XSL-FO, but if your documents are originally in DITA or DocBook then it would be better to use DeltaXML DITA Compare or DeltaXML DocBook Compare.
We are looking at demand for a DeltaXML XSL-FO Compare product and would like to hear from you if you are interested in this.
There would be a number of output options from this, the most obvious being showing added and deleted text/graphics. Another option, which would preserve the page layout of the original document, is to show only additions and marking deletions with a single character, even if a lot of text has been deleted.
Please contact us if you would like to discuss this further.