In my experience it is useful. 2 to 4 dunks oportunities can make a difference when exploted properly ;)
Same goes for 2-4 blocks a game, or 2-4 timely three pointers, though most BB users beg to differ about the importance of Shotblocking and Jump Range, evidently.
Now, the question is would you take 2 to 4 dunks per game, if it meant that your team as a whole missed 4-5 extra 3s per game? It is all relative. Because to get a SG to proficient inside shot means that you are not training him in other skills.
Run of the Mill Canadian Manager