I use the focus display all the time in "action shot" scenarios – kids and pets. The auto focus is too slow (at least on the X100, X-Trans was supposed to fix

I use the focus display all the time in "action shot" scenarios – kids and pets. The auto focus is too slow (at least on the X100, X-Trans was supposed to fix this) to capture these, and I can't manually focus quickly enough through the LCD either. It's similarly useful for low-light shots. The 3rd-party CHDK firmware for Canons has a focus display as well. Loved it when I had a Canon for the same reasons.