They are intended to provide a more economical means of installation compared to a conventional install.
They are more difficult to service because they are not easily (or cheaply) removed from the hull and typically requires removal of the engine to get the shaft out.
From a performance standpoint, they don't load as hard as a conventional pump.
Moving the hand hole cover outside of the boat should have been a no-brainer from the start. Should you ever need to access it while in deep water, removal of a hand hole cover that is located inside the boat would cause an immediate 4-1/4" diameter geyser to spring forth.
