We do some monkey-patching on MSVCCompiler as well, but mostly because distutils doesn't define a good way to subclass or configure a compiler class.

IMO, monkey patching is a really bad idea. distutils should be evolved to provide more proper extension mechanisms like the ones via distclass and cmdclass.

That said, we only use the compilers that Python itself is compiled with for each version, so your change should work for us (modulo some fixes we'd have to do to support it).

One detail you are not considering with your patch is that distutils can well be used to build other tools and those may need older VC versions. Couldn't you at least keep the old compiler support around in a separate file ?