Documentation is insufficient: I don't see how someone can *know* how to use these from just reading the docstrings. That is easy to fix, however.
my opinion is so different than the consensus, that it probably doesn't matter much in this respect... but i'd rather spend the same time on writing documentation on how to use slime or on shaping the code. this is for developers after all, if they don't know how to C-c RET or M-. then a docstring won't save them... :) imho.
my docstring for switch would look like this: "Similar to CL:CASE but compares using a user supplied :test function." (if i was forced to write one for a 10-liner, that is... :)
Finally, there is a question of style/consistency: unless I am mistaken, CLHS has no examples of macros with :TEST and :KEY arguments. Should the syntax be :TEST #'FOO, or :TEST FOO?
switch (and other similar macros) support #'foo already. see EXTRACT-FUNCTION-NAME.