The father rearward the spoilers are mounted, the more they act like an inverted split flap, and the more proportional control you get from them.

If you think about a spoiler mounted at the thick point, it doesn't take much deflection to completely separate the airflow from the rest of the wing. by the time it's up 10 deg. the wing is fully spoiled. There is no more lift to be killed. Functionally, you only add some drag by deploying the spoiler further.

The spoiler mounted further back is more proportional, as it takes more deflection to kill an equivalent amount of lift and creates proverse-yawing drag in proportion as well. It actually will start to show some of the properties of inverted split flaps, as it will actually start to deflect air up and create a relative high pressure area on the wing skin in front of it, to create the rolling force.

THe MU-2 uses spoilers for roll control in part because then the whole trailing edge can be used for flaps. That allows this tiny-wing airplane to slow to halfway sane landing speeds. Having the spoilers in front of the flaps serves to magnify their effect on roll control, even at slow approach speeds.

I had slot-lip spoilers on an Oly2 glider that I had built with slotted flaps. That was great for glide path control. With flaps 60 deg out, it would descend at a pretty steep angle, maybe 25 degrees with the nose pretty level. Pop up the spoilers on top of this, and it would decend steeply, but slowly at maybe a 45 deg angle, with the nose level. You could easily see thru the wide gap beteween main wing and flap when approaching like this. Cool gadget for sure.