I don't understand the diffenrence between FeatherDance and Reflect, the effect is pratically the same, so the problem is restored.
How Haze-Reflect Hawk worked:
T1: Switch into Stat-Up mon as it Stats Up.
T2: Haze, take eh damage.
T3: Set up Reflect, take lol damage or watch the opponent switch.
T4: Roost while your opponent switches or is rendered ineffective.
T5: You have 3 Reflect turns left, do whatever.
How Haze-Feather Dance Hawk works:
T1: Switch into Stat-Up mon as it Stats Up.
T2: Haze, take eh damage.
T3: FeatherDance to further weaken or Roost to get back health. Against SD users Feather Dance will cancel out. Against DDers they net +1Spe -1Atk.
There are no Reflect turns, state of play is basically neutral and opponent has to switch if it can't address Haze/FD Hawk, however the next threat does not start out dealing with Reflect protecting the entire team and its potential switchins.
Tomohawk must then use Feather Dance each turn to replicate any new switchin starting with reduced Attack, and any turn Tomohawk is using Feather Dance is a turn it is not attacking or switching to something more directly threatening. Contrast Reflect where Air Slash (or Earth Power) became a no brainer option because Reflect would be in effect regardless of opponent's switch or stay.
Used with a concrete example, you have to leave MMeta with -2 Attack before leaving the field to net the same effect for a switch. With Reflect MMeta was nerfed against the entire team for those 3 turns and not just trying to overcome Tomohawk itself. Tomo could actually switch out and back in against MMeta with Reflect still up in that timeframe and repeat the process.