IPv6 filtering at network edge?

[Pete Ashdown]

I'm tightening up some network-edge filters, and in the process of 
testing filtering with IPv6, I found that there is a lot of ICMP 
link-local (fe80::) to ff02:: activity at an IX.  Is any of this 
necessary?  I am wary of over-filtering that cuts down functionality and 
doesn't increase security.  What of the IANA-reserved IPv6 addresses can 
be safely blocked on ingress/egress at the network edge?