lisp: dynamic scope vs explicit parameter passing

I see two different patterns for "output" functions in (common) lisp:

(defun implicit ()
  (format t "Life? Don't talk to me about life!"))

(defun explicit (stream)
  (format stream "This will all end in tears."))

(defun test-im-vs-ex-plicit ()
  (values
   (with-output-to-string (stream)
     (let ((*standard-output* stream))
       (implicit)))
   (with-output-to-string (stream)
     (explicit stream))))

Is using dynamic scope like in implicit considered bad practice or is this a generally accepted use of dynamic scoping? Note that I'm assuming this is for e.g. a DSL to build complex output, like HTML, SVG, Latex or whatever and is not expected to do anything different apart from producing a printed representation.

Are there - apart from style - any important differences, e.g. with respect to performance, concurrency, or whatever?