I've been on multiple other kinds of subways and trains across the state, and I can't say there's ever been more than the 10 minute lag needed to purchase a tram pass (a one time act). I don't know how even the strictest HSR would compare to the TSA process and the sluggish seating process of a plane.

The commute may not be different in the long term, but as of now LAX's traffic is legendarily bad, even by LA traffic standards.