Hopefully, I'll learn more and whether it's applicable to the leak from Cornwell's article in that back issue. My understanding now is that the mechanics of the pump is a cyclic building and releasing of pressure. One valve allows water to build up speed, it shuts, pressure builds (creating that 'high head pressure'?) until another valve opens to the upward pipe.
The one negative I've read is just what you stated: only a tiny bit actually goes uphill.
