I am using 10/256 as the lowest setting in my custom SRK driver (Custom SkyRay King SRK Driver) Works fine with all the LEDs that I have tested (even after some considerable heat soaking tests) It puts out considerably more light than a moonlight mode… plus I am driving 24 ’7135 chips. I don’t see 9/256 as causing any problems for a eight chip driver.
I started out with values around 4/256, but as the driver was put through its paces the required value needed to reliably light the LEDs kept creeping up as it aged and burned in. The threshold shift was permanent.