RE: How high is too high?
Anything above 30 feet is too high in my opinion. I used to be one of those that was against going anywhere above 20 feet, but after reading several articles concerning string jumping, I changed my mind and my habits.
I'll try to paraphrase what I learned and make it simple enough to understand.
When you're hunting from a lower stand, say 12 - 20 feet off the ground a deer that 'jumps string' will be jumping out of the way of your arrow. If you're in a stand 25 - 30 feet off the ground a deer that jumps string, due to the angle of the shot, will be jumping less away from you and more toward you. You've got less of a chance of making a poor shot on a nervous deer from higher up.
I realize that probably makes absolutely no sense the way I wrote it out, but the article made it clear. I'll see if I can't find it. If I remember right it was an article written by Chuck Adams. I'll see what I can find.