It would be pretty sweet if the babel-brunch plugin could use the options defined in the .babelrc file, if it exists. Something like this should work.

JSON.parse(fs.readFileSync(path.join(__dirname, '.babelrc'), 'utf8'));

I haven't thought much about the load order of using .babelrc options vs brunch-config.js options. I'll let smarter people who have stronger opinions worry about that.