Not to beat a dead horse but it seems the pressurization schedule of the T-45 could be a contributing factor in some of these hypoxia incidents.

Consider the T-2C. It has a 5 psi differential. The cockpit begins to pressurize at 8,000 feet and maintains that 8,000 foot cockpit until 23,400 feet of aircraft altitude after which the cabin climbs from 8,000 while maintaining the 5 psi differential. At 27,000 feet of aircraft altitude the cockpit is still at 10,000 feet. The aircraft is also fitted with a separate LOX system that provides 100% oxygen that is available for altitudes above 27,000 feet or anytime the crew elects to use it.

The T-45 has a 4 psi differential that pressurizes at 5,000 feet but doesn't reach full differential until 40,000 feet of aircraft altitude (which I imagine is rarely reached in everyday flight training). At an aircraft altitude of only 14,000 feet the cockpit is already at 10,000 feet. Anything higher and the crew needs to be on the OBOGS system.

Just seems like a big difference between flying at 27,000 feet in the T-2 with a 10,000 cockpit and reliable, separate 100% oxygen system available if you need it and being in the T-45 at 27,000 feet where the cockpit is at 16,000 feet and you have to be on the OBOGS system which has serious reliability issues and no real back-up.