Out of curiosity, how long is your delay and have you adjusted it over time? It's rare that I will think of some modification to (or the need to retract) a comment in the first minute or two after submitting it, so the only delay I could really see myself making use of would be 4 or 5 minutes. I'd be interested to see how many people use this, how frequently it comes in handy, and whether or not it's been fine-tuned to fit the way they think.