If you're optimizing between local versus experience arbitration attorney, I'd prioritize the latter. I've never felt like my geography was a major hindrance (maybe I had to put in some extra hours to learn local laws/rules/customs, but that's rather easy).

Put differently, I feel much more like a fish out of water when I'm out of an arbitration context I have a lot of familiarity I'm with than when I'm under a different state's laws.