I solved the same problem in another way with:

* collectd

* collectd to graphite plugin (for server-level metrics, from all your servers)

* graphite

* statsd (for custom app metrics over UDP)

* graphene - my own UI toolkit for graphite, also based on D3.js (http://github.com/jondot/graphene)

All in all, I got a better, more robust and detailed solution using these components. Using Chef, the time to set it up is very minimal.