I think the approach will be fine, although there are some important considerations when naming the metrics. Because Graphite will store a .wsp file for every metric name you'll have a difficult time re-sizing or adjusting the storage settings should you decide to change your configuration. Additionally, the Graphite UI will have a "folder" for every metric name so you can easily make the UI unusable.
Graphite recommends that "Volatile path components should be kept as deep into the hierarchy as possible". This essentially means that if you can push the parts of the metrics that are frequently unique to the end of the "bucket" without impacting your grouping queries you should try to do so.
Here is a great post on using Graphite that includes naming recommendations. And here is another one with additional info from Jason Dixon (an excellent source for Graphite stuff in general).