I did something similiar a few years back in Venice Beach, CA. Focusing was easy b/c I was using 400 speed film and it was usually f/16, so I hyperfocused it. The images came out sharp. The neat result was the unusual, generally non-symetrical framing. I didn't put my Leica on the sidewalk though, preferring to hip shoot. I had alot of fun w/ it and the fotos remain some of my favorites. Good luck.