gcc is a good compiler, but I do not see much sense in using mingw in Win32, when Microsoft compiler is free, compiles faster, result is half in size and about as good in speed and when MSC++ is much better integrated with Windows.
Supporting mingw takes too much time for me, because it has a lot of win32 integration problems. Thus: I am not deleting "COMPILER_MINGW" from U++ sources, but I am not going to actively fix any issues w.r.t. Mingw myself. I am however willing to apply any patches submitted.