Why is it that sometimes I get the loud double beep when I put on my key, and sometimes a quiet one, and sometimes nothing at all? It always starts/runs fine, so I thought it was rather odd.
No, the beeper isn't important in the fact that your ski will still run.
It is important that it's the warning system that will keep you from cooking your engine if it's overheating. I hear it a lot.... "My ski has never run hot"... but all it takes is running over one sand bar, though one patch of grass, or over one shopping bag floating in the water. Any of that can plug the intake of the cooling system, and leave you stranded because of a dead $9 beeper.