You'd be amazed what the mind can do. As long as the walls are vertical - it's as though that's your ground and you dont' feel very high at all. Problem is when you hit a ledge where you can stand after days with nothing under your feet, you really feel "up there", or when you drop something and remember gravity and you are reoriented back the "right way" - your new vertical reality becomes unseated & you get a sense of your height.
I loved 300-2,000 ft high climbs, actually I have to admit I was naturally more comfortable there, than in water. I loved the exposure - no fear unless the moves got really tricky or weather rolled in.
But one time I felt dizzy vertigo while climbing on day 7 of a 10 day wall when we hit ledges after 5 days of smooth slightly overhanging wall. It was pretty hard to climb while fighting the feeling that came from gazing down the slightly overhanging walls of El Cap in Yosemite which stretched out 2,500 - 3,000 ft below (that's over 1/2 a mile!).
It was kind of a crazy expereince. But not really that different from dropping down to mild narc depths in the deep bottomless blue next to a steep underwater wall
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I'd help you down - Buddy 
