FWIW even though there doesn't seem to be much in it from those numbers, since I switched the C: drive to the m.2 drive from the 840 Evo things seem a hell of a lot snappier, just during general use it seems more responsive.
I don't know how the crystal disk different read and write tests stack up to real world use though so I can't say for sure, but it certainly feels much quicker and it's only the AHCI drive running in the native mobo m.2 slot which doesn't even let it run flat out I think.