On a HHV basis per kg carbon:

DME is indeed a decent contender as an energy carrier, not as good as methane but on par with LPG. The real upsides are:

• Its handling is similar to LPG and it can be stored as a liquid in low pressure tanks. Big difference with methane (very high pressures or cryo).
  
• It works as a nearly straight fuel for HDI diesel engines, contrary to LPG. It just requires a lubricant additive for high pressure injectors.
  
• Its thermochemical synthesis can be very selective, compared to, say, a straight-chain alkane synthesis by Fischer-Tropsch, which yields a little bit of everything from methane to heavy waxes.