The MRJ will only be 15% composite. Mitsubishi had a partnership with Boeing on this. They separated ways in 2008, and the MRJ went to an aluminum construction base.

Boeing is the only manufacturer trying to build in composite on a large scale currently (A corporate jet manufacturer built and test flew a composite barrel, but then the economy went south, so they shelved it for now - I think this was Raytheon). I'm sure Airbus is watching closely, but even their A350 design is a metal barrel, though I don't doubt that Airbus is tinkering in a back room on the idea, and could ramp up production if Boeing's barrels are successful in normal operations.