Another question: What about FastSPI_LED2 would make it more sensitive to dirty power supplies? I have two versions of my ws8201 RF controller. One utilizes FastSPI_LED2 and one uses the Adafruit library. I was using the Adafruit library with some 5v 3A wall wart power supplies(50 pixel strings) with no problem. When I run the FastSPI version there is a lot of jitter/interruptions/blinking of the lights when connected to the same power supply. Replacing the supply with a decent 5V power supply and the FastSPI controller looks perfect.
FastSPI is driving the clock/data lines at a higher speed than the adafruit libraries are - the chipsets seem to be more susceptible to noise at higher speeds.