Configuring all nodes as seeds

[Peer, Oded]

My intended Cassandra cluster will have 15 nodes per DC, with 2 DCs.
I am considering using all the nodes as seed nodes.
It looks like having all the nodes as seeds should actually reduce the Gossip 
overhead (See "Gossiper implementation" in 
http://wiki.apache.org/cassandra/ArchitectureGossip)
Is there any reason not do this?