Rendering resolution and refresh rate on Pimax 8K?

Could someone from @PimaxVR, @Matthew.Xu or those who already reviewed Pimax 8K (whatever version), confirm what is the rendering resolution used currently on the demos?
In other words, what is the supersampling factor used by Pimax to counter lens-warp?

Second, could someone confirm at which FPS the demos are rendered?
And for those going to the shows, could you check both frequencies 75 and 90 Hz and see what is the difference in the latency?

I am still trying to understand the performance requirements for the gfx card, and it seems no review or hands-on published so far has it addressed. For me it is quite important to confirm before the KS ends.