I'm quite surprised Heinz at your wear rates. I covered 24,000 miles in my 4/4 Sport and had the standard pads, I replaced them at 17,000 miles as one inner pad delaminated from the steel backing plate. I never needed to replace discs.
I never experienced any wobbling due to the disc being out of true.
My two pennyworth says that Green Stuff are too aggressive for the original discs and that you need to fit uprated grooved discs maybe for a little extra cooling, it sounds like the OE one's are cooking?
