well attwood makes an OK bilge pump, but these are not intended for continous use, notice they dont give you a life expectancy in hours like a fish or pond pump would. I doubt these pumps would last 6 months continuous use, as they are designed for intermitant short length duty cycles.
I have a Rule24 bilge pump that I converted to inline and 1/2" fittings. It's rated for 360 GPH at 13.6 volts, but I am running it off the red and black wires, hence 5 volts. I have had no problems running this thing non-stop, both at 5 volts and at 12 volts (though admittedly the pump is relatively hotter and louder at 12).
Anyway, if you don't see me post for a while six months from now, I guess you were right Otherwise, I haven't had any problems.