I've been under the assumption that setting the media type (Canon PRO-100) changes the amount of ink used and maybe something to do with thickness. Maybe timing too? Is there any way to convert the media types to some numbers so one could better understand and choose them?

Bummer. I was envisioning something like a 2-axis graph, with ink on one axis and whatever on the other, with a dot showing where each choice lived. Being a measurement geek, I wonder if one could measure the mass of a piece of paper, printed with each choice, to determine how much ink was deposited? Need a sensitive lab balance, but seems possible.