"Whereas SRFI 27 allows the user to get the state of any source,
however": The "however" can be removed.

"Random-port states can also be compared" Operations on random port
states are only specified implicitly earlier in the paragraph ("external
representations"), so "also" should be removed here.

"SRFI 158 generators, however, are ill-defined" this makes it sound like
there is some inconsistency in how generators are defined, when it seems
like the point is that generators are too simple. "ill-defined" should
be changed to something else.

"See e.g. Taylor Campbell’s comments on preferable defaults" His
comments aren't an example of the previous statement. "e.g." should be
removed here.

Overall a very nice elephant.

-- Peter McGoron