Very good points. I agree 100%. However, I think you can and should mix the two. I write mission critical code in C++ with all compiler warnings enabled and lots of unit testing. I do less critical code in dynamic languages (such as Python) where I can 'import critical_cpp_module' and use it from within the dynamic environment. This approach allows for the best of both worlds. I get the benefit of quick development time, high-level Python libraries and the ability to be sloppy without being punished while at the same time I have strict, very strongly typed and tested C++ code for the things that just have to be right no matter what. When you combine the two approaches, you're more flexible. I suggest Boost Python for those who wish to expose C++ functions, classes, etc. to Python.

Edit: Software such as pylint are nice too if you're going to go dynamic only. That helps catch lots of bugs that you'd not otherwise notice.