I assume that the references to "sim" are to the in-house e-cab <
Boeing: The ?e-cab? ? a test flight deck>? Which presumably has software that is at the same level as the test aircraft, or slightly ahead as a last step in verification before loading to the aircraft?
<<The simulator is equipped with all of the controls and hardware that pilots will use in a real airplane, and it's the closest thing to flying without leaving the lab. New to this e-cab are the larger flight deck display monitors. The four 15-inch (38-centimeter) monitors of the 737 MAX are the same as in the 787 Dreamliner. "Being able to fly the e-cab before flight testing gives us the chance to practice our maneuvers and try out the new electronics systems that drive the flight controls for the new aircraft," said Christine Walsh, 737 MAX Deputy Chief Test Pilot. "It's a chance to feel the airplane before first flight."
"We've coined a term that has become a very important focus for us: right at first flight," said Keith Leverkuhn, Vice President and General Manager for the 737 MAX program. "It means making sure that by the time we put the airplane in the air for the first time on our flight test that we know how these systems are going to act and that they are mature enough. If it weren't for certification requirements, the systems would be ready to enter our customers' fleets.">>