Thanks Michael and Philip! Interesting datapoints.
Weird that the Nikon scanner makes Pro 160 look grainier than Portra 160.
In Ctein's article, Pro 160S was slightly less grainy than Portra 160NC.
Whereas Portra 800 was noticeably less grainy than Pro 800Z, all colors.

I was going to buy these four films from B&H, but they were sold out
of the camera I wanted, so I guess it'll have to wait. My test would've
been done on a Fuji Frontier and HP Photosmart scanner.

Also it would be worthwhile to compare Pro 400H and Portra 400NC. Fuji
has no film to compete with Portra 400VC, so I guess that one could be
tested against Ultra Color 400. I've heard/seen nothing but good things
about the new Portra VC films.