I went from a 8350 overclocked to 4.7ghz to a 6700k at 4.5ghz and i gained approx 40fps on X Plane 10 and also approx about the same in most of my other games that I play such as Far Cry Primal, GTA 5.
I think if you have, say a 970 or lower then AMD is the best bet, financially, but as you progress up the GPU ladder, thats when intel really shines.
Matt
Bear in mind his 6700 runs at 3.4Ghz..... There's a reason why they are much cheaper than the 6700k's that can do 4.5Ghz+ easily.
What is yout 6700 boosting to in games? Single thread it will do 4Ghz, though not too many single thread games these days, 3.6Ghz multi-threaded?
That said, even at 3.4Ghz it should still wipe the floor with your AMD setup. I'd recommend doing some benchmarks (firestrike, cinebench r15), compare with others using the 6700 nonK.