Ok well it is a requirement of the TS specification that "The analytical methods and acceptance criteria used shall conform to those in customer reference manuals on measurement systems analysis."
So there is no escape there, then!
Although I do find it rather odd that in the years I have been involved in completing gauge studies the question of stability, bias and lineriarity has not been raised either by the customer or an auditor. Is this going to be this years "beat em up" topic on audit I wonder"