I can't comment on what LinX does, and if it is applicable here. There may be some confusion also, in that although the instructions used are FMA, sometimes they get lumped in with AVX2 since they were introduced at the same time.
I don't see a 6600k listed in your computer list. Have you ran actual units through it? You should see a nice speed out of the 6600k, depending on what clock it is running at.
If we assume for now that the 6600k was overclocked to 4 GHz like the 2500k, I would expect it to see about 1.7x faster runtime on it for PPS, PPSE and SGS units. Not MEGA as that is getting bigger and will start to be limited by ram speed.
In case you wonder why, Sandy Bridge (2500k) didn't support FMA which was introduced with Haswell. In my testing this is about 50% per clock faster so it gives a big boost. Skylake (6600k) didn't add any useful new instructions, but they did something to make it more efficient overall and it is about 14% faster at Prime tasks than Haswell. Combine the two for about 71% speed increase (the boosts are multiplied, not added).