We had a couple scares last year when the furnace humidifier drain line plugged and dumped all over the basement floor, so I installed a couple of the Harbor Freight water detectors at critical places. Thankfully (maybe?) the Monitor 70's didn't seem any worse for the wear of sitting in wet carpet. Now had they died, I'd have had a better reason to upgrade....
We also have a sump pump, but it's plumbed into tile drain lines under our slab. We'd need about 2 inches of water in the basement before it began spilling over into the pump basin from the surface of the basement floor. It seems like it could have been done differently, to where the sump could take any water ponding on the floor in a worst case scenario where the floor drains aren't working. But maybe it's a code issue or something.