We actually looked at VulcanD in an older version of Empire. When we decided to use a routing layer with this version of Empire, rather than just letting Empire/ELB expose each service (mostly because it is a lot easier for us to later shut off public access to each service) we threw together nginx because it was so simple.
I think at this point everytime we move a service we add like 5 lines to an nginx config, re-deploy the router in Empire, and the service is exposed.
The internal 'service discovery' makes this a lot easier, since we just have to tell nginx to route to http://<app_name> - no domain, no port, nothing more than the app_name thanks to DNS/resolv.conf search path & ELB stuff.