All the cleverness in the world is useless if the resulting design performs poorly. This in fact is where we met the most resistence from C programmers. The premise of most criticism is that C++ code leads to inferior executables, either bloated by support for C++ capabilities, or somehow merely unoptimizable.
Much effort went into proving by example that tight and efficient C++ code is certainly possible. Since we chose to stick with a specific compiler, we had the luxury of studying the output assembly code and working it until the assembly couldn't be further improved. That experience has led to some generalizations.