Definitely one of the more interesting topologies I've seen.  Are you using the Auto VPN feature between the MX's?  Can't remember if I asked that but that would connect the two as if they were local to each other regardless of what is in between.  That link from CiscoRouter 1 through Core to the top firewall gives me a little concern.  You have a potential routing loop there if you're not careful.  ... View more