That's actually a pretty interesting-sounding use-case which makes me want to fix action=.xml, but I'm not sure when I'll get around to it. Probably not in the next week or two, at least. (I can't just enable it, since it's too slow; I have to rewrite at least some of it.)
Okay no worries. Is there a way I can follow along and/or get notified when it is ready?
You can simply click on 'watch' and 'notify' button on the top right side of the thread. Any replies posted here will give you a notification via email.
In case Theymos decides to fix the xml issue then he might reply on this thread after fixing it which will give you a notification for the same.