I think the real argument for testing vs. types is that for most jobs "programmer productivity" has to do with producing code that works in practice rather than

I think the real argument for testing vs. types is that for most jobs "programmer productivity" has to do with producing code that works in practice rather than code that is perfect under all possible circumstances. Most of us are not developing satellites, nuclear power plants, or pacemakers. Premature optimization for robustness probably wastes more programmer-hours than premature optimization for speed. That said, if you haven't used something like ML or Haskell you can't possibly imagine how many subtle bugs can be caught by a type checker, particularly edge and corner cases that will eventually dominate your test suite - in the unlikely event that your code lives that long.