Interesting points. Here is a few things you'll miss choosing Route 53 over ELB:

* HTTPS termination.

* Autoscaling group management. By connecting an ELB to an autoscaling group, the logic of registration and deregistration is fully managed behind the scenes. With route53, you have to implement it yourself.

* Minimum autoscaling group size. If you enable ELB health checks, you can rely on the ELB to maintain a group of instances of constant size.