They will have to use a heavy weapon system to down an Apache... that kind of thing is not easy to hide (particularly after having fired a couple of bursts) - historically when they have tried it the Wing aircraft is the one that spots the tracer or muzzle flash/dust and has destroyed the firing point. Hence they don't try it very often.
As for the comment from SASLess about "I thought the Yanks liked to brag" - it was not a "brag" simply a fact. They don't like AH and are not that stupid that they will try and take us on.
I take it that you have recent operational experience of flying AH in theatre?
Thought not.