I have just a few small comments:

* In the description of `regexp-fold', in "...calls finish with the same argument," the word "argument" should be plural.

* In the paragraph describing `rx-match-submatch', the sentence beginning "if an integer outside..." is confusing.  I suggest changing it to "If passed an integer outside the range of matches, or a symbol which does not correspond to a named submatch of the pattern, it is an error."

* The phrase "desirable to want to" should just be "desirable to."

* I agree that <- would be a better choice than =>.  Perhaps now is the time to make the change before SRFI 115 is set in stone.  There's a great story from the original author of Make.  He said that he decided early on that he couldn't reverse the decision to make SPC and TAB have different meanings -- a terrible decision -- because he already had ten users!