:lolAt the distance IRs are shot grill cloth would be negligible. However if you want to go down the carbon battery, wire directionality or solder type rabbit holes I'm all in, NOT!
An engineer who worked with EVH told me that a hole in his grille cloth was part of the sound, but thought that this was mainly due to the fact that it allowed the mic to be even closer to the paper. Here we can see it also naturally affects the high end a bit. Cool.