I completely agree with your other points, but I just wanted to address this one. I was a CFI before I went into the airlines, and while I learned a ton teaching, I also matured immensely as a pilot "flying around on autopilot." Not picking on you specifically, but I've heard that same argument from many CFIs, and I probably made the same arguments myself before I made the move.

Trust me, you'll learn just as much, if not more about flying by flying turbine equipment in line operations than you did teaching. Me personally, I learned how to think ahead and plan, what really matters flying IFR (I used to teach a lot of trivia I came to found), and I became a much stronger and smoother instrument pilot as a result. I'm flying six-pack equipped props again and having flown a more automated jet has still made me a better pilot by far.