The performance difference between dev and prod builds of React is significant in my experience. In tests of an animated interface (fairly heavy app otherwise as well), a prod build did 2-3x the raw FPS of the dev build.

I can't really imagine what type of benefit they believe they're getting. Your error tracking system does re-assemble the stack from a out-of-band delivered sourcemap, even in prod, even with multiple versions deployed simultaneously... right? Like any decent error tracking system such as Rollbar or Sentry will do out of the box. Tell me you didn't build your own and can't even unwind a production error trace.