does Saxon 6.5.2 support
http://www.exslt.org/exsl/elements/document/

I use the latest stable Saxon for example. I switched from saxon:document (IIRC) to XSLT 1.1 document. I could switch to EXSLT, but what I currently use works well, so there's no need to change. Again: it's up to each programmer to decide if he wants to rely on extensions or on drafts. I agree that well-specified extension features are a more stable base than W3C drafts, but I don't agree that the latter is the wrong choice in all situations.