First off, 20% of your run income vanishes into taxes to your corp. (It's pretty much assumed any runner with a legal SIN has some kind of money laundering scheme in place to pay their taxes).
Secondly, You'd basically be treated as having the negative quality Records on File (Run Faster P 158-159) with your parent corp.
Your SIN, and thus vital statistics, are part of the Global SIN registry meaning law enforcement around the world can check for matches against your records.
Although your corp may not be hunting you (as long as you don't do runs against them), rival corps may decide your a valid extraction target.
Then various RP elements of how much people may or may not hate megacorps in general, or your corp in particular.
To add to this:
IF you are ever found out to have a legal corp SIN by the shadow community, you are a pariah at best, and a hunted man at worst. The general line of thinking is "You live in the Ivory Towers, yet you're here slumming, thus you must be a plant/mole, or Law Enforcement."
Remember: IF you have a legal SIN, that means ALL your info, including Aura (for awakened) and genome are on file. Its not a question of getting caught, it's a question of leaving any viable evidence at the scene of a crime.
A Corp SIN: doesn't provide immunity to police. Corps have reputations to up hold, and consumer goods to sell..... Getting a reputation for allowing wanted criminals to hide on your property does not inspire sales. You ARE just a cog after all, not a VIP, elite member of the board of directors. (who would be protected, just by why they are!)
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This is a quality you should really hash out with your GM before you take it. Many people have such differing views of the pros and cons of this quality, it's a good idea to know what and how your GM will apply those pros/cons. Your GM may take a liberal view of the quality and everything is fine. Or, he could take a very harsh view of the quality, and the first drop of sweat of leave on a run, 'Mama Corp' comes kicking in the door to turn you into a 'protected asset'. (IE: Little bitch on a string)