The competitive "A" series from Airbus is already running the more efficient jet engines.

In addition, there are also incorporating weight reduction via increased use of composite.

However the biggest thing(s) that is being missed, is the costs related to :

1. Airline fleet commonality. If you are running A319's, you want cockpit training flexibility, which running a different plane will not allow.

2. The delivered cost of a plane can offset the operating costs of a plane. If the Airbus rep is telling you that you will have to double training costs (new cockpit) to run the C Series, then that opens the door to Boeing, who will YES sell at a loss in order to steal a customer from Airbus (and vise versa)..Look for both to lower the cost of an A319, or 737-800 to come close to the cost of a C Series - without the hassle of new crew training, spare parts, maintenance, etc.