I fitted a Morgo because I needed a pump (I thought mine was good, but) and wanted to eliminate as many variables as possible. I can't say that it cured my wet sumping problem, since, I also changed the timing cover (in case the original was warped) and fitted an extra paper washer; I cued the problem.
The pump seems to run well although my normal running pressure is IOR 22psi (assuming the gauge is accurate).
I fitted a Yamaha reed valve to the machine (crank case timing side) which meant that leakage of oil was minimal. However, having rebuilt the engine (the old bore was shot) leaking and ejection of oil from the breather has improved further. I o think that a worn bore can cause all sorts of unwanted side effects.
So, the verdict on the pump is that its ok, but if you have a good Ariel pump it will be more than adequate for the job. If your bore is good, check that there's not an air leak in the oil return circuit before changing pumps, etc.
AOMCC Member 4296
1950 Rigid Ariel VH
1951 Rigid Ariel NH (under construction)
1973 Norton 850 Commando Interstate