Vent System
I do not know the changes that have been made to the vent syste. My understanding is that it impedes the airflow from one wing tip to the other. Vent is necessary for the vented fuel tank to allow one cfm of ullage mixture to veent out when one cfm of NEA is supplied to the fuel tank. If there wasw not one the fuel tank will get pressurized and structural damage may occur.
I think a better system is a inerting system that does not use an inert gas. This is described in SAE aper 2009-01-3134. It cn be downloadedfrom SAE website. It requires no modification of the vent system and does not discharge hydo carbon laden ullage gas. There are other advantagess too. I strongly suggest review of the paper "Method and System for fuel tank inerting without an inert gas."