The addon to bridge ExpressionEngine with XenForo is finally here - http://www.eevolution.co.uk/products/xfee . If you prefer to add to your devot-ee account the link is https://devot-ee.com/add-ons/xfee
XFEE hooks into the ExpressionEngine login procedure to both sync member credentials (great...
Thanks to a sponsor who will be named upon live release, we have finally achieved a Xenforo <> EE bridge [XFEE] in a similar way to our VBEE product http://www.eevolution.co.uk/products/vbee . The solution is in private BETA but should be released to the public next week. If you are interested...