Are you scanning any of your Superia negs? Cuz it's when I get into scanning that I really notice the grain -- or lack thereof.
Hrm . . . I decided that, before I malign Superia 400 any further, that I'd take a closer look at some of the negatives I shot. Welp, as it turns out, those that had a fair amount of overcast or shade in them showed quite a bit more grain than those that were taken in strong sun. I suppose I've been holding this impression in my head because I've only shot a couple of rolls of the Superia 400 and most of the photos were taken in overcast or darker conditions. So, based on revisiting my images I guess I need to revise my opinions toward Superia 400 somewhat. The well-lit photos look good. Still, it has more grain than Memories, especially more chrominance grain.