I'm with Sothron on this one. First off, getting Dark would give us 10 deep - 2 quality players at each position. Second, we have no idea how well Smoove could play at SF because he's been forced to play bigger. I think it only helps us that he can play bigger, but he could become much more productive if he had a chance to focus on one position. Plus, he can stay trim and athletic at SF, whereas he has to beef up more to play PF. Horford and Sheldon can hold down the 4. Zaza and Dark could take care of the 5. Speedy and Law have 1, JJ and Chill at 2, and Smoove and Marvin at 3. Of course there will be flexibility to play big or small depending on the situation, but that's the beauty of it.
The way to get Dark is to trade AJ or Lue to DEN for their TPE. That would give us enough space to probably get Dark. The only trick is the contract length.