Never heard of showing an empty chamber, usualy just holstering is considered safe.....
It is evident from your above statement that YOU have not/ do not shoot IDPA.
The rule book, page 11 C 18. Range Commands states the following,
H. Unload and Show Clear.
I. Slide Down or Cylinder Closed.
J. Hammer Down.
Then and ONLY then is the RANGE SAFE. PERIOD
I have omitted the range commands A-G as they do not pertain to the discussion at hand