min is 1, DATA_RATE_KHZ if you want lower. Max is, well, could be pretty high - but realistically you’re limited by what the underlying hardware’s max is likely to be, which is roughly 24Mhz on the teensy 3, and 8Mhz on the arduino.
The Mhz/Khz are a bit rough/loose on the bitbang’d side, by the way
Yah, I don’t think the teensy will have any benefit for the POV. 
It’s the PWM that I need to address … a 16MHz AVR can pump data out plenty fast.
This does bring me to another question: how safe is it to have four strings of 48 RGB pixels on the same set of pins/port? Since my design will have 4 strings, all displaying the same exact data, why not drive them all together from the same pins/port.
Perfectly fine to do that - i’ve done that with 4 150+ led strips branched off of a single port.
Ok, I can put all of them on the SPI port then and just blast data out like a bat outta hell.
I love the presumptions some people make, good times.