BTW, why is Fearful considered such a big issue?
The first time we did Zorn and Toth on hard mode was with four melee DPS (one Shadow, three Sentinels). The tanks just swapped the bosses between each other (so the tanks stayed in the same position throughout, only the bosses moved). The DPS on Zorn's side only had to pay attention that after the jump, they start hitting Toth instead of Zorn, immediately.
When we actually tried it with ranged DPS it caused all sorts of nightmares in positioning and such. It was far easier to just revert to the "groups swap the bosses" routine which, as far as I can see, has no downside.
The downside as already pointed out is how punishing Fearful is someone screws up. The other things is the DPS loss which can be an issue if your DPS is low/undergeared. Not a big issue for you configuration as you described it since 3 of your 4 DPS can leap to the boss instantly and the other has force speed you have almost no DPS loss. Compare that to a group with a couple slingers and a gunnery commando (what we usually run with) and try doing swaps like that and watch your DPS plummet due to the constant running your turret classes now have to do.