Update: after talking to several folks intimately familiar with the Foveon sensor, I believe we can say the following. First, while everyone, including Sigma, keeps trying to use the RGB nomenclature, the Sigma sensor is most certainly not RGB. It's more like a luminosity layer at top (with a color bias), and then color difference layers below. It's much more similar to Lab Color than RGB color. Second, a number of factors start to come into play with the current sensor, including diffraction into the lower layers and even reflections between layers. As it was, some advanced Foveon aficionados were already using averaging or blurring techniques on the lower layers to "smooth" them. In essence, that's what the new sensor design does in hardware. Apparently, this was an approach that Foveon themselves had considered at one time. The expected gain from this approach is likely a greater than 1 stop but less than 2 stop gain in ISO performance without any real impact on acuity. Given the 14-bit change (from 12-bit) and some other changes in how the signal is processed, we might see a 2-stop gain, which means most folk would find ISO 800 acceptable. Too bad Sigma's marketing wants to get into technical discussions that are wrong instead of just saying the obvious. For example, they could have just said "the new approach is usable in X stops less light without sacrificing the high acuity of the Foveon sensor. Coupled with other changes we've made, the new DP's will be usable in more conditions, operate faster, and yet not give up any of their resolution advantage over Bayer designs with the same number of pixels." (...)