Ah, I meant on the Pimax 8k HMD. 
…although, for all I know, the images could very well go across the DP cable as regular 16:9 1440p at 180Hz (…or rather 160, now with the 80Hz), rather than as a side-by-side stereo pair, the way it does with Rift/Vive. In addition to keeping with the usually expected 16:9 aspect ratio, this should make things simpler on the HMD end (just alternate the switch for the destination display, dealing with one image at the time, and then sync up the global refresh), and also make brainwarp a bit of a (cringe) no-brainer… 
(EDIT: …ultimately slightly easier on the HMD end, than normal mode (EDIT2: …since you don’t need to wait for both buffers to fill up))
EDIT3: Might as well… So, the problem with brainwarp, as I see it, it that whilst the main body of the rendering load will be the same as regular 80Hz simultaneous, the game will need to update physics and animation twice as often. Much of this is CPU bound, and may already be pushing the limits. I expect it will also prevent us from beginning to “share” (I am assuming this is as of yet very rare) culling and setup stages, between the two view planes.
On the upside: Better physics fidelity. :7 (EDIT4: …ragdoll stuck between door and floor can now oscillate twice as spastically )