Yeah good topic! One of the first variables I play around with when I get a new coffee is alter the dose/grind to see what plays better.
What is your reasoning for having a lower dose for the blends and not the single Os?
One of the other things associated with down dosing with a finer grind is the freshness of the beans. Ive heard around the tracks that to get the best out of uber-fresh beans is to fine it up and down dose.