1.  I see in on line 87 of property-test.sld

        ;; Inexact (integers and non-integers)
        (cond-expand (gauche '(0.0 0.5 -0.5 1.0 -1.0))
                     (else '(0.0 -0.0 0.5 -0.5 1.0 -1.0)))

Does gauche not have -0.0?

Similarly for inexact-complex.

2.  The SRFI 27 random number generator generates a range of integers
between 0 and a bit under 2^{32}.  To generate numbers greater than this
requires several calls to the basic generator, using arithmetic shifts
to assemble the random integer from random "words" of size a bit smaller
than 32 bits.

So on a 64-bit machine, fx-greatest is going probably going to have a
width a bit less than 64-bits, so the default random integer will take
2-3 calls to SRFI 27's basic random number generator for each random
fixnum generated.

If we're going to stick with generating fixnums with these integer
generators, then I think it would be good to have a max-int width that
takes only one call to the SRFI 27 generator.  So that would require a
max-int of around 2^{28} or less.

Brad