if youve got a terraforming candidate, especially a remote one, this will let you build up bodies and mines on site while the terraformers chug, lets you get kind of a rolling start. it also saves corundium compared to automines. corundium crunches are deadly but they only seem to happen as a result of building lots of automines.
i would definitely take off the cargo capacity. dragging orbitats is rage-inducingly slow already, and since youve got to devote shipping to this plan anyway, just ship the mass driver separately. also, you'll probably want to deploy them in numbers so the cargo capacity becomes highly redundant.
id just leave the mass drivers out of the equation entirely, tho apparently this is a minority viewpoint. with asteroid miners often you wind up at a site that you mine out fairly quickly, and just picking up all the minerals when you come back to redeploy the miner is fine, and i imagine similar use-case with this set-up. mineral packets are the devil anyway, and having a mass driver operating far below capacity is pretty wasteful of both in-game and cpu resources.