This is a nice article but for the life of me I can’t see the GRE tunnel come up automatically. My setup is based on a CentOS 6.4 distro and the setup is almost exactly the same as what you have here. I may have some settings on my router config which may perhaps clash with the GRE tunnel. WCCP checks appear to be correct however.
I have used tcpdump on the wccp0 interface and doesn’t appear to be any traffic going over it.
I do have an ip nat inside command applied to my router interface and the router does have another ACL which permits the subnet any. I’ve seen other examples of this which appear to use NAT but prefer this method, just wondering how to troubleshoot this further?