Yes, Bosch does test there sensor at 1000c. They do not suggest ever running it that high. The suggested max bung temp from Bosch is 550c, this does not mean the best case senerio but rather the max it should ever get to. Running anything at the max it should get to is going to take away from it's service life. I have personally seen the readings change after a number of pulls with the bung in the downpipe. Not sure why you are wanting to argue the extreme when it should be easy to see that running the sensor farther back will keep the temps lower and lessen the chance of false readings and premature failure.