This exists but now you're limiting your audience to use APIs and syntax in a slightly newer, different version of node (io.js). I'm not convinced that's worth

This exists but now you're limiting your audience to use APIs and syntax in a slightly newer, different version of node (io.js). I'm not convinced that's worth it in my opinion. I'm not sure npm can support using the same package name deployed under different engines (it doesn't appear to as far as I can tell) but that's annoying to maintain.