As the summary suggests, there -may- be a bug in the way the radvd.conf file is generated. Using:
Tomato v1.28.20111009 MIPSR2-beta-tomato-RT-N-GIT K26 USB Ext
Basically, in the GUI my prefix length is specified as /56 with an assigned/routed prefix of '2607:f2c0:xxxx:yyyy::'. In radvd.conf however the prefix length is set to /64 - the net effect being that all of my local machines end up in the yyyy subnet directly. Not a super critical issue as the /56 I've been assigned is massive overkill given I only have 10 or so devices on IPV6, but may be an issue in the future.
Can anyone confirm and if so can confirm this is in fact a bug?