Early Decision after you've already done at least one application cycle

Does anyone have any experience (positive or negative) with applying Early Decision after you've already gone through the application cycle? It occured to me that if you were on the top tiered waitlist of a school, you are considered "competitive." So, what if the waitlist doesn't move enough and you don't get in? You've gone through the process and probably have a better idea of where you'd "fit" than you would have before.

So, in returning to the question: has anyone done this? Heard of this? Have any opinions about this?