A civilian mining colony will only have a level 1 DSTS, regardless of how many CMCs there are. I believe there is one mass driver per CMC, or 1 per ten mines.
I had a CMC on Titan (that had 7 different minerals with availability more than 0. 7, I rigged it. . . ) with almost 25 CMC (equal to 250 automine), and they deliver more than five thousand tons of minerals each year. . . So, it seems true. . .