[xsl] XML Diff and Merge

Hi all, Do you use any visual XML Diff tool to compare the results of XSL
transforms? I've had a look at these:

- IBM Alphaworks produce an XML Diff and Merge tool that sounds perfect.
Unfortunately it doesn't run under recent Java VMs (I tried it).

- StylusStudio - has XML Diff under Tools > Show Differences in > Files - it
does indeed show the differences and they are nicely presented and colour
coded but the individual files are not editable and differences cannot be
applied.

- oXygen XML Author has a Diff tool that works well and allows merging of
changes in either direction between a pair of files. It also has a simple
command line that should allow it to be started automatically from a CMS.

Do you know of any other tools I should be considering? Specifically Free
Software or Open Source would be good.

Thanks,
Richard