Thanks for the continued comments.
Yes, all of the major corporate interests will have at least a token representation in the upper city. The "Upper City" is almost like a corporate mall in which the University is the hub. But, perhaps everyone "plays nice" up there. They all realize that it is in their best interest to be near the University's research and so are uncharacteristically cooperative, each contributing a member to the governing board (not dissimilar to the Zurich Orbital Court.)
So, shadowruns in the Upper City would be rare, and ultra-hush-hush.
The Lower City is another story completely. It's all but abandoned by the corps, and there really is no government. Organized crime, gangs, and ghouls pretty much have free reign so long as they don't impact the biz of the upper city. The dragon keeps to himself. The corps pay a tax to keep the DMZ's enforced, but that's the extent of their involvement.
I like the Casablanca direction. A good hidey-hole for runners to base and launch their operations into other locales. They learn very quickly not to stir up trouble in the Upper City. If they can learn the rules of the street, the Lower City provides a fertile ecosystem of weapons trade, biotech trickle-down and data leakage.
I'm also trying to decide on the logistics of the elevator between the two cities. I was originally thinking of a platform roughly the size of a medium warehouse that worked via a complicated combination of cabling, hydraulics and mag-lev technologies. The damn thing would always be breaking down at the most inopportune moments.

Any better ideas? What about a catchy name for it? "Skybox", "the Lift" ?