I agree on both. APE is technically impressive and Cygwin could be more elegant. But for solving the problems with cross-Win-Posix-development it is quite good and relatively elegant.
I think cross-Haiku-Posix-dev is much easier than Win-Posix. At least so it seems to me. And I don’t know about cross-Win-Haiku-development. The best solution are ported libraries in my opinion. And C libraries are usable from C++, Python and what-not-else. Most programming languages don’t produce libs in that universal way.
Greetings
Peter