I will register my strong vote for staying where you are unless you can get admitted to HYS or possibly CCN. Don't fall for the siren songs of crappy CA law schools in a seriously oversaturated CA market.
Also, you cannot count on getting special treatment from your firm if you went to law school. Sure, they will give you an interview, but if you don't meet their school and grades cutoff, they won't hesitate to reject you. Really. The school and grades cutoff, meaning where you have a viable shot, not where you definitely get the job, for a V15 in SoCal are probably:
-anyone except very bottom of the class at HYS (S preferred)
-median (at the bare minimum) from Berkeley
-top 1/3 from the other T14s, keeping in mind that some of them are more portable than others
-top 10-15% from USC/UCLA
-top 10% from Davis, Hastings, and UCI (and we have people on this board from these schools in the top 10% + Law Review who completely struck out with big law, let alone V15s)
-top 5% from Pepperdine/Loyola
-top 5 people from Chapman
-anywhere else (Southwestern, Thomas Jefferson, etc): no chance
Perhaps you can expect that because of your connection to the firm, if you are top 25% at USC instead of top 15%, they might give you a call back. But don't go to some heap-of-dung school like Southwestern and expect a V15 to hire you from median because you used to work there. It won't happen. Also, you have to realize that getting hired in big law is a numbers game: the vast majority of successful people have good school/stats and get face time with many firms. Having a connection with one firm isn't that helpful when it is a numbers game, unless you are in their range (see above) or at least borderline.
On to the question of how URMs perform in law school: people who are saying there is not evidence of this are incorrect. There is evidence that URMs get lower grades in law school, on the whole. The good news is that, as 'on the whole' implies, that doesn't prevent you, the individual, from rising above that. The person in this thread who took big money somewhere I expect is at no disadvantage. The further good news is that studies have shown that even though URMs are more likely to get lower grades in law school, their careers are not negatively affected, at least if you go to an elite school like UMich, where the study was done. I would hesitate to extrapolate that to a random CA T2 like Chapman. Any underperformers there, whether white or black, will have the equally bad outcome of unemployed debt slave.