A number of the routes that the 789 might be considered for require an EDTO of at least 240-min. The recently promulgated NZ CAA rules require 2-years at 180-min before applying for 240-min and another 1-year at 240 before applying for 330min. Additionally, I believe the IFSD rate gets tougher as the diversion minutes get higher. A "young" engine /airframe combination like the 789 is going to take a while to mature and some IFSD's are likely during the maturing phase. 240- or 330 min are quite a way off given the expected EIS of the 789.