Well I did a partially blind comparison in that I got a bunch of prints and compared side by side and sorted them into piles of either 'really nice and sharp' vs 'fine but not as good as the others' then went back to the negatives and saw which were from 35mm and which from 6x7. I was surprised to find that there was a difference even in 5"x7" prints. I thought I might start to see differences at about 10"x8" so I was a little surprised to see it in even these smaller prints. Obviously the RB67 is suited to some types of photography and the 35mm to others but it was interesting to see the difference in prints that small. The difference for me was in the tonality, hard to define really, but there was a smoothness to the prints from medium format. For me, that's the justification for taking out the RB67 when I can.
You should see the tones you get from an 8x10 negative, contact printed.