Quoted from DesertPinGuy:
The color inserts on the pinbot 5x5 grid are so nice you can't go wrong with doing all white leds.
I added color to each of the three Pinbot machines I have owned. I use white led for the yellow and color match the rest. For me, the real deciding factor is the amount of fade to the blue inserts. It seems like a lot of the blue inserts on pinbots I’ve had were washed out or faded. The color led really made them pop again. But with perfect inserts, I do not disagree with your opinion that all white led will be nice.