I had Doug of Diezel UK explain the mid cut to me and it was something like this;
I asked, mid cut? why not just turn the mids down? what's the difference?
and he replied something like imagen a sound wave, when you turn your mids down sound wave goes like this *\____/* if you get the idea, when you turn it back up it'll be either the opposite or like this _______ depending on how much you do it, but what the mid cut does is instead of just cutting out the mids, imagen this soundwave *\____/* where the asterixes are, that's the middle point of the soundwave, that the \___/ is still there but the line in the middle of it is parrallel to the asterixes, so you have the raised section on the edges but it dips it down in the middle of the soundwave.
anybody understand that? nope, didn't think so...
But in context of sound it's alot harder to here, they're also called 'scoops' on some amps if I'm not mistaken, try to here one in person, it sounds alot more metal cutting the mids rather then just turning them down and you'll get a better tone in my opinion that will still cut through.