We get conflicting results everywhere and I suspect that temperature has a significant impact on this.Somewhat surprisingly, it seems that the IQ3100 has close to 15 EV of DR (per pixel), quite impressive.
BartvanderWolf at lula measured 14.39 EV, while I measured something slightly above 14 EV.
There's a site called "iRentals.cn" (the Chinese equivalence of LensRentals.com). According to their review, the IQ3100 has less DR than D810 does at pixel level, and this is prominent for long exposure of 30s. The IQ3100 needs to downsample to show its advantage of DR over the D810. (The last plot attached here is the "effective number of megapixels remaining to achieve 40dB SNR for shadow after downsampling".)