I tried Ralf Koban's and it works really well. Having this as an option is probably going to now be worth buying. I think that solution as is could be integrated by semanticmerge pretty easily.

You can use external parsers for that (I've written some):

.csproj, .sqlproj, .vbproj, .xml:
https://github.com/RalfKoban/xml-semantic-external-parser

.resx:
https://github.com/RalfKoban/resx-semantic-external-parser

Maybe they can help you on merging.

It shouldn't actually be too hard to implement either, as I've shown in this answer to comparing XML-files: http://softwarerecs.stackexchange.com/a/20676/14982. You could of course do this hidden, but as proof of concept my answer shows that it is not that difficult to compare/merge XML-files.

Another pain is to merge XML elements containing values separated by semicolons, like "AdditionalIncludeDirectories" in a vcxproj file.

Any news from the staff on this? It is one of the top requests.

this would improve the support of csproj, xml, config, cshtml, html, resx, xaml...

Yes, I find that csproj and sqlproj files are the hardest to merge. If this tool could be aware of xml nodes being moved within the project file that would be insanely helpful. I have not been able to find a merge tool that handles this correctly without resulting in duplicated entries in the project.

Yep .csproj, .sqlproj, .vbproj.... they're all a gigantic PITA to merge. This would be a fantastic time and stress saving feature.

Merging resource files is much more pain than merging code with text-based merge tools. Code files are usually relatively short so you can get the diff sooner or later. But merging big resx files as we do every few days and the VS designer reorders them alphabetically, this is simply a nightmare. Buying semantic merge would be a no-brainer for me, if it would support merging resx (or xml files in general).

Also, I believe this would be the solution to merging csproj files.