ive got both.. its nice to have 2 taunts.
generally taunt is more of a dodge buff for me and i use it as i engage a boss.

as i mentioned before: i think beckon does some damage as well as stuns

another interesting thing that seems to work for me (when grouping with fools that don't wait for the tank to engage before going balls out on dps) is stomp, beckon , stomp ... ping pong the boss around. its pretty funny too when you see it