I updated to the correct AMD VR drivers last night and lots of succesfull runs, performance remains an issue though when near ground or an airfield,
i5 4690k @4.4
R9 290X 4GB
16GB DDR3 1600
SSD
I also used LCTRL and Pause to check FPS and fluctuates from 100 to 150 (Thought the rift was 75 locked?, but was very juddery when not at 150), Also said VRAM useage was 4.3GB on medium settings and 4X MSAA, this is very high to me and more than the 4GB on the card.