I have them… shall I just solder them in?
What difference would it make if I didn’t?
If you don’t solder them in, you would need to put jumpers in their place. They are “current sinking” transistors. If you opt out of them, you might be OK if you don’t use bright LEDs, but if they draw too much current you will destroy a shift register IC.
If you have them, there is no disadvantage to using them.
Just the answer I was looking for. Cheers mate.
Back to the bench…
They are not really optional. The firmware expects them there (it inverts the outputs so that a high DOUT pin causes current sinking). You would need to modify the source code to not invert the outputs. Not really worth the effort, since they’re there to sink more current than the shift register can handle by itself… i.e. sinking current from 16 LEDs.