The big draw, which I'm seeing on my 5x hunter group as well, is that 5x DPS is minimum 25% +dmg over a 4x dps + 1x tank/healer and even more than that over a 3dps/1heal/1tank makeup. Now, how many talents would you give up for +25% dmg? :P And it scales infinitely. Throw that in with a group that isn't that squishy and has a ton of utility AND heals AND wipe prevention and, well, you see the results.