Assuming you fall into the camp that doesn't want to see arbitration used to destroy all collective rights (which camp includes plaintiffs' counsel explicilty and defendants' counsel covertly), here is some good news, compliments of The UCL Practitioner. The U.S. Supreme Court denied a petition for writ of certiorari in Brown v. Ralphs Grocery Co., 197 Cal.App.4th 489 (2011). In Brown, the Court of Appeal (Second Appellate District, Division Five) held that representative PAGA claims (i.e., not class-based claims) are not subject to arbitration, even post-Concepcion. That's Concepcion, the case, not the other option (with different spelling).
Get your PAGA letters ready.