I would prefer to keep Bruce here as he is a superior keeper to Davis. Do you think he\'d deal Davis for Dunn? To me that is something I would consider doing.
IF I am dealing for \'position\' i.e. fill my 3B - I\'d want someone of equal value just at a differnt position. I just dont see Bruce as equal value to Davis here. Depending on scoring format (i.e. if Batting avg. or K\'s are included) Dunn is more expendable and would allow you to keep Bruce. It would not solve your McCann/Iannetta problem but I dont see a problem in trading McCann if that\'s something you are willing to do. Getting appropriate value for McCann CAN be an issue (I\'ve had problems in the past). IF you are able to flip Dunn for Davis - you don\'t have to fill a specific Position in a trade for Iannetta/McCann which makes it easier to trade.
If I can\'t trade someone else to land a 3B - Huff and or Cantu aren\'t ideal but not terrible options considering the offense you have at other positions. I\'d go Huff over Cantu here but not by much esp. if H Ram is batting 3 to Cantu\'s 4th or something like that.
Hope I helped!
Good Luck