When I first got my G37S, I was pretty much clunking everywhere. My GF was a bobblehead due to this and said I need to man up and learn how to drive the car properly.
I usually wear athletic type shoes. Some adidas bounce, nike shox, air force ones, and some other random assorted shoes.
After I got the hang of the car a bit more, I found my self clunking a lot more in certain pairs of shoes. It didn't dawn on me that shoes with thicker soles were either muting more feeling from the clutch (not that it really gives us any to begin with) or giving me slightly more travel that it was causing me to inadvertently mess up.
I've since found that shoes like nike tennis classics, or any thinner-soled tennis shoe...adidas has a bunch, and soccer type shoes like the Air Gatos work really well for me. These weren't my preferred type of shoes before but I find myself going for them just because of the way it changes my control of the clutch. I hate wearing any type of dress shoe in the car.
Anyway, just my random observation. I was shoe agnostic when I drove an automatic, but now my behavior with the 6MT in wanting smooth shifts + clutch longevity has definitely affected my shoe choices.
Maybe it's just me...