I have had a dual Conceptual Polymer catch can setup on my 2013 5.3L since about 1000 miles on the engine. A CP standard filter unit as a primary, and a high efficiency unit inline after it to separate anything that got by the first. These engines are prone to issues due to the AFM cylinder shutdown thing, and catch cans have shown some benefit. I capture about 1oz or more of oil out of the PCV line every 1000 miles. Even more so in the winter due to condensation and such. So, In the time I have owned the ride, I have capture just under a quart of oil and junk out of the PCV line. I wold dump what was caught into an old 16 oz drinking water bottle, until I filled it up to the threads on the cap and now don't try to keep it. I was interested in how much, and how long it would take, to capture junk. I suppose some don't mind dumping a quart of oil and crankcase particulates into their intake to coat and junk up their valves, but I have problems with being comfortable with that. I would think that those with newer DI engines would be all over putting a PCV catch can setup on their engine.
As for it increasing combustion and power, oil in the combustion chamber via being drawn in thru the PCV, can reduce the octane rating of the fuel in combustion. That is why some performance folks like catch cans.