2 perks, not 4. Izual suggested changing bonus move to 4aps per each.
Actually youre not right man. Creating BG 1LK based, gives you free perk slots on 6 and 9lvl. You cant take BRD, or Toughness. The only 'pvp' perk you can take as a tank is Quick recovery. But thats not pure evil perk. So, bonus move is right choice if you want to pwn in TB.
For now this perk in TB isnt overpowered, because, as u said, you do less damage, but u are more flexible for 1 vs. swarm situations. But after that suggested upgrade, it will be overpowered for sure.