Not to start a needless back and forth, but I've worked in both static and dynamic languages on projects large and small as well. I do believe that unit tests are the biggest improvement by a long stretch for re-factorability, but a good type system simply eliminates whole swaths of error cases, and modern systems don't require a lot of overhead either.

Another advantage for some strongly typed languages are the complex, yet safe refactorings they enable automatically by a good IDE. This is not universal though, and is a serious downside to picking Scala over Java.