So the pump comes on whenever there is water use? An accumulator is superfluous? No water hammer issues?

Super quiet? --- Our pump is near our bunk and not especially quiet... That's both bad and GOOD (if there's a water leak).

Does the pump vary its output according to demand?

Our existing one (shuffle?) with accumulator has been fine for 12 years, but will fail sometime. We'll probably not change it while it still works.