Nice idea, but how to deal with my frequent copy/paste actions in the definitionss window of DrRacket?

For sexprs, copy/paste is easy in the definitions window of DrRacket. Just copy/paste and reindent. How easy would this be with sweet expressions? Can we copy/paste at a choosen level of indentation?
 
Say I have a definition
 
(define (f a b c)
  def/expr ...
   last-expr)
 
When I am not sure that function f produces correct results, I modify it temporarily as:
 
(define (f a b c) (let ((r (let()
  def/expr ...
  last-expr)))  (printf "result of proc f: ~s~n~n" r) r))

Notice that here the indenting is deliberately wrong. Using the temporal "let ((r" form I don't care about the indenting. After seeing what is going on I use ctl Z in order to remove the extra let-form and the print-form. How would this be with sweet expressions?

Wish you good luck. A sweet expressions language is certainly possible in Racket. If i can be useful for (parts of) the implementation,mail me privately.

Jos