Yes, I believe that baseball should have a dedicated instant replay umpire because this allows for calls to be made with close to one hundred percent accuracy. The more accurate the calls are, the more fair the game is. Instant replay allows for this accuracy and adds to the integrity of the game.
Baseball is one of the sports that could benefit a great deal from a dedicated instant replay umpire. Trying to figure out if a player is safe or out when sliding into a base is something that is very hard to be accurate at predicting with the live human eye. An instant replay would make it very easy to determine the correct call.