I will say it again - read the article in Soaring magazine - then comment. Opinions and anecdotes are fine, but I think we would rather bet our lives on actual data. The FAA "guidelines" were set circa WW II and were not based on physiological realities. The article explains the onset of hypoxia, and contains test results on a variety of individuals showing that the FAA regs are severely out of date as to onset altitude. Incipient hypoxia occurs at low altitudes (5-8kft), regardless of age and conditioning. Incipient does not mean disabling, but it is the start of (probably unnoticed by the individual) degradation of performance. The article does not address the question of whether individuals living at high altitudes (my house is at 6400 ft, but I turn on the O2 before taking off from Moriarty at 6200 ft) experience the onset of incipient hypoxia at higher altitudes. The article recommendation is on the side of ensuring sufficient O2 from start to finish of flight by those who have run and documented test results.