I didn't read this whole thread but:
1) I believe the lobe style oil pump we use in in fact a PD style pump. It sure isn't centrifugal.
2) I'm not sure if we're arguing terminology or actual effect but I do believe a HV pump can create problems with a system that was already marginal when it used a normal pump is used. Part of that reason might be that pretty much every HV pump is also HP - high pressure. Without parsing all the details....if you have a stronger pump a-suckin' your oil, and the oil can't return fast enough, you can suck all the oil there is to suck.
A stock system, let's say, returns oil just slightly faster than it can suck it....so the pickup stays covered and happy.
Change to a more-sucky pump, and more oil is being sucked but nothing has been done to the system to improve the return. The pickup gets uncovered.
So while Tim Melling might be correct that an engine's tolerances determine how much oil you can 'use', that's at a given pressure. But raise the pressure? That equals more oil flow.
I could also believe that an engine's oil use is at times determined not by the tolerances, but by the oil pump/pickup itself. A stock pump might well run out of capacity at times...the engine would allow more oil to flow if the pump were to push it. But, the pump doesn't have the lobe capacity to fully satisfy the engine's ability, so you get less flow. Change to a HV pump and all of sudden the bearings are flowing more and the weak player becomes the sump capacity.
A big Achilles heel of the oil systems we use, for the most part, is the gravity return. Trying to route all that oil, too past a spinning crankshaft doesn't help matters.
