FWIW, I edit XML in vim plenty. It's not awesome, but it's not particularly painful either. XML is not unfriendly to $EDITOR, but it is more verbose. The great value that XML provides is in technologies like XPath, XQuery, and XSLT. I ache for the power of XSLT in association with LyX.
But also, even if LyX adopts a native XML format, the old .lyx format will necessarily stick arou d for a long time due to the need to support migration from one format to the other, so it should always be possible to edit .lyx in $EDITOR for those who want it. The .lyx format can't be going away forever anytime soon! Regarding collaborations... there's an online, web-based, collaborative LaTeX editor out there that is clearly superior to LyX as far as collaborative editing goes. It'd be nice if LyX could grow some awesome collaborative functionality, and I think that XML technologies can help there. Nico --
