I had no instances of serious altitude illness (hape or hace). My experiences while at altitude includes hallucinations (cho oyu 93), fatigue and diminished mental clarity. Slight shortness of breath in Telluride after climbing stairs etc, even after several years in Telluride. Discernible lightheadedness and increased respiration at 13,000+. Without supplemental oxygen, paragliding in Telluride (12,000 to 17,000 feet) has given me a headache the day after.