What specific features are your referring? msxml3 isn't complete and has a lot of problems, but it's considered as ready, it's enough for msxml4 to just forward to it. If there's a real problem let's add another forward (as DOMDocument40 already does).
After some more investigate the crash is caused by fixme:msxml:domdoc_setProperty Unknown property L"SelectionNamespaces" XPath error : Undefined namespace prefix xmlXPathEval: evaluation failed
Which is already covered by a bug already.
Best Regards Alistair Leslie-Hughes