14.9 PE-CE Routing with EIGRP
Unlike most questions, this one is pretty straght forward. At first, I had problem figuring out just how the useful the evaluation of the cost community is. To see the difference it makes you can try disabling it, by adding the following in your bgp process:
bgp bestpath cost-community ignore
By doing this, only EIGRP routes show up in the routing table which turns the backdoor link into the prefered path for everything.