I agree. The one time in several hundred games of civ I researced DR, I regretted it.
One situation I would research it is if I was pursuing a Religous Economy strategy in which you build the Spiral Minaret, University of Sankore, Apostolic Palace, and the Sistine Chapel. I've heard that this can be a very powerful strategy because all of your state religion's buildings net you 2 gold, 2 flasks, 5 culture, and 2 hammers on top of what the building already gives you. GO RAMSES!