Yeah, I say to make sure you plug up the hole, empty your sump, then unplug the hole. See exactly how much water flows into the sump before the water level gets below the point at which its drilled. Measure how much water ended up in your sump, because that's how much is going to drain out in case of a power outage, then just make sure you leave atleast that much extra room in your sump for the water to flow out of.
Or if you're concerned the the hole is too low, use some pipes or an overflow box with teeth to make the overflow higher. The pipes might be an ugly fix, but either will be a way to control the water level better.