I usually shudder at duck typing and/or GC for anything bigger. Both have the ugly tendency to explode in your face at runtime. The first type of error doesn't occur in C++ (at runtime), and in the other instance I feel like having more control. But maybe my academic experience with the two is to blame (multi-person projects in python (multiplayer game using lecturers lib) and Java (SQL DBMS, GC killed performance while in C++ I would have written a specialized allocator)).