I've just noticed the Zyxel P660HN-51 (http://us.zyxel.com/Products/Details.aspx?CategoryGroupNo=PDCA201019) claims ipv6 support - dual stack and 6rd - but there is no mention of it in the documentation.
Does anybody have first-hand experience of this device? I've very tempted to pick one up for evaluation next time I'm in the US.