Since the OEM pump changed from plastic to composite, the weak point is no longer the impeller, but the bearings. The new OEM composite impeller doesn't shatter like the old OEM plastic ones did.
So, your question should be more specific: Which one has the best bearings and bearing seals?
Anecdotal evidence suggests that the bearings on the aftermarket pumps aren't as reliable as the bearings on the OEM (reman) pumps. I know of no empirical evidence to back this up, though.
The Stewart pump, regardless of its "improved" pumping volume, has a lifetime warranty. That doesn't mean it'll last forever.
Originally Posted by GoingNuts
You are incorrectly.
I don't need evidence, I just know.