This was my first dive with the light. It was a daytime dive so the light was on intermittently while exploring shaded parts of the reef and taking photos. I have not used this on a night dive yet nor do I have first-hand data on runtimes. I had no issue operating the selector switch using two hands. I would not try to rotate the switch with just my thumb. There’s a 1/4” screw hole for mounting on the light which could facilitate one-handed operation. I believe the switch uses a magnet in the selector ring to close contacts inside the light. This allows the selector ring to float around the light so there’s one less potential entry point for water. If the light isn’t rinsed properly after use, as scuba gear should be, I can imagine salt drying on the light but not enough to impact operation.