hi,
well, i can understand your hesitation about redirection but, you know, actually YAMS does use that $_SERVER["HTTP_ACCEPT_LANGUAGE"] var i was suggesting you to make a snippet with when redirection is set on "browser"...
reading your first post, i was surprises by one thing, for a recent website i've used the last release of YAMS (1.2.0 RC3) and, at least one of the behaviors you're looking for seems to be what yams does, the fact that when you come back to the website, you've got it in the language you'd choosen during your las visit.
This is achieved by setting the redirection mode to "current" or "current or browser"
one thing that may help it working like this is to put * in YAMS config "MODx URLs" field because, when you do this, yams doesn't retreive the language information from the url (the /en/, /fr/ part) but sets a cookie to manage languages
have swing