I've had good luck with the Johnson UltimaSwitch. Two installed, one failure in ten years. Pumps are both in bottom of a fairly shallow bilge but switches are mounted at different levels, one switch on a 300 gph Rule to keep the sump as dry as possible is mounted as low as possible. The switch for the 3700 gph is mounted about six inches higher. Both pump switches and pumps are on a hot battery
bus when house power is not selected on and will run until the battery charger
and/or shore-power fail or until all 460ah of battery die. I wouldn't trust a Rule, or any other float switch when the boat is unattended. Must have gone through a dozen or so over the years and besides most, especially the Rule flapper type, can get jammed on or off with debris. I do have a Rule flapper type for my ultra loud, ultra obnoxious bilge alarm
(also on the hot battery bus) but that switch is just below floorboard level and hopefully never gets wet or subject to debris. That one works fine, sometimes too fine. When really heeled over on a starboard take it will come on and scare the crap out of everyone. I guess I should mount it fore and aft instead of sideways.