I shoot 400 speed almost all the time. And the only time I shoot a slower film like FP4 is when I want longer exposure times shot on a tripod. I often use filters during the day, and in bright sunny condition with a polarizer and orange filter over the lens 3 stops are absorbed, so I may be shooting at f/8 at 1/60th of a second hand held. This could never be done with a 100 speed film. The only time I can get away with shooting a 100 speed handheld is when I'm shooting the lens near wide open. But then again my fastest lens is f/4. If I were you I'd keep shooting the 400 speed for everyday stuff and find a faster film for inside the bars like Delta 3200.