Well, the shoulders are buffed on the ptr to I think 40% for their damage buff. This is good, because it means you can take DA and using a CD on DT isn't a lose of damage anymore and is in fact encouraged. The boots are number 3 or 2 over all depending on your gear. So that's not bad. I think bracers and the KJ are still top dawg though.
Bracers are getting nerfed to one or two additional wounds, down from 1 - 3.
Many are guessing shoulders will be the new go to leggo depending on how much AotD lines up with DT once you have t20 4pc as UH.
The biggest issue you'll likely have switching is getting to high mastery. This can be painful, but honestly get to 65% mastery and you're be in a decent spot to start to get a feel for the spec. UH has a lot more going on at all times. In fact, UH is its most simple if you take DA as that's all about pumping out DCs.
Just start ToS as frost and aim to get high mastery gear and then swap once you have it. The key is your weapon, not the legendaries.