Effects of hypertension at high altitude.
May be hard to coordinate a study, but if there were climbers with hypertension, I would really be interested in the effects of high blood pressure on acclimatization.
There was a study on tibetans in which the researchers found that the native tibetans had much lower levels of hemoglobin in their blood when compared to other groups of people living at similar altitude (study used people in the andes), I also saw this correlated to nonnative Tibetans who live at altitude in tibet, theres an interesting longitudinal study comparing tibetans and han chinese infants, living in Tibet, from birth to adulthood, that examined this as well.
One theory as to the lower levels of hemoglobin and the comfort at altitude, without the traditional physiological changes (such as increased hematocrit and Hb levels) to adapt to the altitude, was the elevated blood pressure, as a result of an insanely high salt diet, especially Tibetan butter tea (salt flavored tea).
Not sure if this would be a feasible study, but interesting none the less, and probably wouldn't be smart to have a hypertensive climber stop taking their hypertension meds while climbing to humor my curiosity, but drink up some salt tea and climb on.