We all know SFR is better. However it comes with a large performance penalty. It only scales around 50% at best.
Did you not read the post above you?
"This graph highlights how frame times and frame rates aren’t the same — according to our first graph, D3D is faster than Mantle. Actually play the game, however, and Mantle is easily the superior solution."
If you split the frame into 50%/50%, 1st GPU has 4GB of VRAM and needs to render ~50% of the workload, the 2nd GPU has 4GB of VRAM and needs to render ~50% of the workload. That's why you can theoretically load much more than 4GB of VRAM into 1 frame because you are splitting the frame's resources. With AFR this isn't possible since GPU 1 renders frame 1 and GPU renders frame 2, GPU 1 renders frame 3, GPU 2 renders frame 4, and so on. This means that at any given frame, GPU 1's 4GB of VRAM is the limit for frame 1, while GPU 2's 4GB of VRAM is the limit for frame 2, etc.
For SRF, it's unlikely that each single frame can be perfectly split into 50% VRAM and 50% GPU load evenly for each GPU, and that's why the scaling is not going to be similar to AFR's. However, it means you can theoretically use both of the GPU's VRAM pools
simultaneously. If your frame 1 is using 6GB of VRAM, GPU 1 could perform 33% of the workload with 2GB of VRAM used, while GPU 2 could perform the remaining 66% with 4GB of VRAM used. Suddenly you are using 6GB of VRAM on 290 4GB CF in SFR.
For anyone who remembers the early days of SLI/CF, SFR was always an option but developers hardly utilized it.
I wonder how it would be received by most gamers. Sure it may run smoother, but you will also see significantly less FPS than AFR. This means the cost of that extra GPU may seem less impactful to them, and cause them to complain about the cost to performance they get. Psychologically, that FPS meter is really difficult for some people to overcome.
That's true if the market is uninformed/refused to believe that frame times matter just as much as FPS, if not more sometimes. There has been a serious push for frame times over FPS for the last 3 years and if reviewers and gamers experience smoother gameplay at lower FPS due to superior frame times, then the metric of price/performance will need an adjustment of what "performance" means.
We know already from early days of HD7970 CF and recent reviews of 960 that FPS does not equal good frame times. It's just ironic seeing how almost all of the major websites that pushed frame times over FPS for years and years are not completely quiet on this point.