Ref the video I posted: I don't think there is any reason to come that far out of the saddle. The higher you go up, the farther you have to come down, and the easier it is to come down hard - which defeats the purpose of posting. My 13 year old daughter posts like the video, and it drives me nuts. And of course, she isn't about to listen to Dad...
I can see what you're saying there! My old instructor used to have me post ridiculously high and it put me off balance more than anything else. My cousin thinks that it might help me to think I should make the movement as small as possible, so I'll try that.