TCCMB Chess Quote of the Week "We cannot resist the fascination of sacrifice, since a passion for sacrifices is part of a chess player's nature."
Rudolf Spielmann
I don't know what you'd do with a survey. My suggestion is to pair the event by preferred time limits. I suspect most of the better players will play at 10/60 and the weaker players will generally play at 10/50 or 10/40.
You'll probably get a bigger entry with such variable times. You'll also get a chance to analyse drop out rates and quality of the play at the different rates of play.