I use a parallel pair of Marco UPE2 gear pumps as my freshwater pump. They are much more robustly built that the other alternatives to the Amel original pump I have seen, but of course you pay for that. I have a fair amount of experience with Whale, Jabsco, and other diaphragm pumps and most of it has been not good. We have had the Marcos in service for a year of full time service and are very happy.
The pressure is listed as "29 PSI" and that is a maximum. We see pressures of 25psi in real world use. That seems low, but with good fittings (especially shower heads) it is more than satisfactory. The flow volume is more than we can use with two users fully open. Having two pumps in parallel means I have a built-in installed spare in case of problems.
LMC, Fort Lauderdale, FL