The (Open_Source) IM gang only supports the msvc compiler on windoz and my research suggests that you have to use the same (32bit) compiler and the same (i386??) optimizations to link to their binary distributions.

But doesn't your Strawberry build link to their binary distributions ?
Mine used their dlls, though I (perhaps unnecessarily) rebuilt the import libs from those dlls using gendef and dlltool.

I get the same test failures as you ... though, occasionally, the montage tests succeed.

Do you know how siginificant those failures are ? (I don't.)
They're not *obviously* of far-reaching siginificance:

C:\sisyphusion\Image-Magick-6.89>perl t/montage.t
1..19
.....
Test 12, signatures do not match.
     Expected: bcd96dabb454c5d25091422763b1cdecb6a69a9b02b84a5b7fa0a70
+f150b957c
     Computed: f1ed563cf9a446dd4516945b475bc21692037d0c12a83405a837abc
+bdf37bcf7
     Depth:    16
not ok 12
Test 13, signatures do not match.
     Expected: 9209b2db884fa4730eeab6c410b90e094fa305635baab7ede17270c
+13f6e80ad
     Computed: c09fb4e6033eb562b277dc2d8d5b61e4255b56ee9c666011d18e4fe
+7fbee994b
     Depth:    16
not ok 13
.....

C:\sisyphusion\Image-Magick-6.89>perl t/wmf/read.t
1..2
mean-error=1.00003051827663, maximum-error=1
not ok 1
mean-error=1.00003051827663, maximum-error=1
not ok 2
[download]

Even the slightest and most insignificant variation would result in a failed signature match.
And 1.00003051827663 is only just outside the "maximum-error".

Cheers,
Rob