The larger Rules are great pumps..I would personaly stay away from the timed/sensing models in favor of separate switch controlled ones..there is absolutely no need to have that degree of sophistication or battrie draw on a boat..it ether needs to pump or it doesn't and nothing does that better then a float switch..
I too have three pumps aboard and the second and third ones to go off are tied into separate audible alarms so if they ever do I know I have issues.
Hope this helps
PS: It has become a habit of mine to hit the switches to the manual position ( one at a time ) every time I board my boat to
1) listen to how much water
is being pumped out ( this will pretty much self test the float )
2) It will also activate the alarms on the other two testing thoes circuits as well. ( do these ones last as you cant hear them pump due to the alarm
3) I sleep well at night for doing it..