The teeth 'angle' was one of the other methods described to me, the AAI chap also mentioned that the brace position was to keep the jaw closed (and the teeth intact for forensic examination) as much as to attempt to alleviate blunt trauma on the neck and spine should the crash be survivable.
As to changing seats, we've all done it I'm sure, it just made me wonder if there was an official stance from the airlines. Thanks for the replies.
SHJ