Looks nice. Comment/suggestion: if there is no reason to have more than one instance of Shred (and it appears not), then require('shred') should just return a new instance.
We do anticipate some applications wanting more than one instance. There are two scenarios where this comes up.
1. You want separate connections per instance. This is useful in load testing, among other things.
2. You want to provide different default options for different instances.
Neither of these scenarios is supported very well in this release, but we expect to add support for them shortly.