I've tested extensively with 980Ti SLI. But I'm not going to weigh in until I've tested again because there have been several driver releases and two major game updates since the last time I tried SLI. For those of you who have provided input, has any one of you tested SLI in Horizons?
I just upgraded my three screens to 144hz monitors and when testing SLI on other games I can not percieve any latency at all, however on my old 60hz monitor lag was noticeable. The higher 90hz of the retail HMDs alone may eliminate SLI latency so it may very well be a plausible option to run SLI in VR.
I'll do some more testing in the coming days with SLI in VR since the major updates and post the SLI thread if people are interested.