After the CO do where I missed my earlier flight, they rebooked me no problem. I was at the airport within 2 hours of my original depart time though. However, per normal, my ENTIRE itinerary was cancelled and had to be rebooked, including the loss of one EUA for the flight home. I had to wait until midnight and fortunately, it did clear the second time again.

I'd re-think the $100, just to be safe. It's actually a pretty cheap insurance policy and gets you a better chance of UG on the later flight rather than just showing up.