Very interesting topic!
When I use my only UHS- II, the Lexar 32gb, my X- T1 starts very slowly- it first shows the display, then I have to wait around 15 seconds, till I see how many shots are left, till the EVF starts working.
After that everything is working as I am used too.
This strange behaviour only occurs with this card in the X- T1, not in the X- E2 nor the X100s.