That impressive 2000GPH pump may only deliver around 500GPH or 8 gallons a minute. I cringe every time I hear the words "for emergency" in conjunction with these small bilge pumps. These are merely convenience pumps to discharge incidental water that accumulates in the bilge and will not have the capacity to fight any significant intrusion of water from a hole in the hull or a fouled thru-hull or hose. At best they could delay the inevitable for a very short time in the hope someone may notice the boat riding low in the water or listing.
For emergencies manual, high volume gusher pumps are utilized
Have you ever used a high capacity pump? Do you think you'd get x strokes a minute for very long to match a "high capacity" electric pump? ;^))).
Also, those manual pumps aren't immune from "head" load. The physics of lifting and/or pushing the water out still is there. (i.e., you have to do the "work" to lift the water). The difference is you're providing the greater number of "watts" with each stroke -- until you can't work that fast.
There is no question that an unobstructed 1-1/2" hole in a boat 2' below the waterline will send an impressive amount of water into a hull! That's a function of the depth below the surface (pressure) and cross sectional area.
The loss of real world performance for the advertised "rating" of almost all bilge pumps sold on the retail market is mostly a function of the height of the water from the pump to the vacuum breaker. The "ribbing" on many bilge hoses (to facilitate installation), the length of the hose, and number/nature of bends in the line, etc. add frictional loss. (There's an esoteric issue of "good" siphon effect behind the pump, but my hydraulics is a bit fuzzy. ;^))))
I believe that various offshore safety standards require at least one manual pump usable from the cockpit; and one from inside the cabin. That's in addition to other electric pumps. (The manual pumps are to be permanently mounted with available handles, "close at hand". If you have a "big" Edson, or other, moveable pump, that's in addition.)
There used to be an expression to the effect that, "There is no faster bilge pump than a scared sailor with a bucket."