UPDATE
So my car went back into the garage that fitted my last set of brakes (these being my 3rd set in 2 years). This garage is an independent Toyota specialist and the owner has worked on IS200's since they came out in 1998.
He put a dial gauge on both discs. NSF was waaaaay out, and OSF was out a little.
He then put dial gauge on the hub flange and both sides were absolutely perfect.
He said he didn't have confidence in the brakes I was using as a lot of drilled/grooved discs are simply very cheap discs imported from china, then drilled in UK and sold on with markup. He is probably right.
So he put on a set of discs from the supplier he uses and has fitted to IS200's for years and years.
I explained I wasn't 100% happy with this solution as this will now be 4th set of discs to go on........so he offered to refund the cost of the discs if they do not hold up after wearing in.
As with before, new set of discs the car drives and brakes like a luxury car should.....if they warp again after 400 miles, I will be back to him for a refund and 2x hub carriers for him to swap over.