I think in the normal reviews 5760x1080 should be dropped, but I think it should be in the SLI/Crossfire reviews. And not really as a comparison to the single cards, so you don't have to bench every card with that resolution, instead maybe just a single page with the performance numbers for just the SLI/Crossfire in all the benchmarks.
I say this because I do think there are people out there doing SLI/Crossfire that are looking at 5760x1080. And, IMO, you should only be running surround with multiple GPUs anyway. So you should present the information, but you don't have to waste time benching every single card.