Yes, it is definitely advantageous (financially) to transfer your ressie.

But the drawback is that you can no longer communicate directly with
DCL. All information after the transfer goes through your TA.
We transferred our last reservation to a TA before final payment was due, for a substantial rebate after we returned (just got it, two weeks after getting back). We had to let DCL know that we were going to transfer it, and then give all the info to the TA - very easy.
A couple of weeks before the cruise, we checked to make sure they had info about a 50th Anniversary and a birthday occurring on the cruise, and also confirmed our dining time (we had asked for main seating on the 6:00 rotation). The special events were no problem, but after we got on the ship, we found out we had the 5:45 rotation, and although we tried to get it changed, we had no luck. No big deal for us.