porque no los dos?

SomeModule.jsx

import React from 'react'

import delicious from './yu.m.css'
import ew from './gross.css'

export default React.createClass({
  render() {
    return (
      <div className={`hard-tacos ${delicious['soft-tacos']}`}>yaaaaaayyyy!</div>
    )
  }
})

webpack.js

export default {
  loaders: [
    {
      include: /\.m.css$/,
      loader: 'style-loader!css-loader?modules&importLoaders=1&localIdentName=[local]__[hash:base64:5]'
    },
    {
      include: /\.css$/,
      loader: 'style-loader!css-loader'
    },
  ]
}