Guru 3d did just that with an older MSI 1080 gaming x . It was about 5% increase at 4k for most games.
Does they have same max non-advertised boost clocks though(Well fast check from tpus reviews, gives 1974 MHz for plus and 1962 MHz non plus, so not that much different).
I am more interested in the GTX 1060. The 8 gb/s version saw MONSTER https://www.techpowerup.com/reviews/MSI/GTX_1060_Gaming_X/27.html performance gains when the memory was pushed to 9.5 gb/s. If the new version can push the memory to 10 gb/s and beyond, it will leave the RX 580 behind. Nvidia always had GPUs that were 1 or 2 levels above what AMD offers, but now it might be 5: Titan XP, 1080ti, 1080, 1070, 1060 9 GB/s, RX580. (Titan X seems obsolete after the release of the 1080ti, so I don't really count that)
Well Titan Xp is still the fastest of them all, only available as reference form nvidia themselves though and extreme price so more prosumer card than consumer. But if money is not the problem and one don't really care about warranties, liquid cooled Titan Xp:s are the ones to beat.