Anecdotally, I use two when I was in LA shooting for the Franciscans. They were the top of the line Minoltas (35mm)at the time 1987. I used a number of lenses. I was building a slide library of people interacting kind of stuff. I had the opportunity to go over some slides done by my predecessor who shot with a Leica.
I was blown away at the difference. The Minoltas were nowhere near as sharp. Ever. I convinced them to get rid of them and buy Nikons and they were better but still not as good as the Leica slides.
I was used to Hasselblad at the time and the sharpness of the negatives and had little experience with 35mm. But if found the difference between the Leicas and everyone else was quite amazing.