it *IS* essential that you match your make utility and your C compiler

Actually, it's essential that you match your make utility with what perl -V:make reports.

I've just built PDL-2.4.6 and a couple of other XS modules using nmake and MinGW without any problems. The tricky bit when building with gcc and nmake on ActivePerl would be making sure that perl -V:make reports 'nmake', not 'dmake'. (I actually didn't manage to achieve that with AS build 1007, though I think it could be done quite readily with some of the earlier AS builds.)

Anyway ... good that you've now got things working, and in a sane and reliable way.

Cheers,
Rob